This theory isn't my personal view on Dumbledore, but rather an idea which could provide an interesting view on that character and possible inspiration. For me Dumbledore was just a character who made numerous mistakes, but wasn't an evil mastermind.
Dumbledore's ultimate conspiracy
I want to thank LeighaGreene for contribution and inspiration.
A big part of the fandom believe that Dumbledore was an evil manipulator, who manipulated Harry and Co to sacrifice their lives in the sake of the Greater Good. One of the reasons for this thinking is that Albus was doing nothing nearly entire series, but only smiling and played a chearful grandpa character. So some people came with an idea that he didn't do much during the first war also.
I'm sorry but that doesn't have any sense. I don't mean a possibility that he was "evil" (although I prefer a word: "realistic" or "gray"). I mean an explanation that the only thing, he did, was manipulating Harry to death and his upbringing to a lack of self preservation. It might be one of of Dumbledore's goals, but we have to look at a bigger political/social landscape. A typical fanom explanation is illogical, does't provide any real answers, but only "Dumbledore was evil and manipulated Harry". But why? Without a wider scene a better explanation isn't possible. His manipulations have to be logical, have reasons. Also there are problems with the "Greater Good", only times when Albus used this slogan was his youth, and we know that youth has its own rules and fervor, so this also needs explanation. The most common mistake is that in fanfictions manipulative!Dumbledore is just an idiot, who really is portrayed a way that he just cannot manipulate anyone and anything.
So if we want to have a logical explanation for manipulative!Dumbledore we have to look on a wider political and social picture. Also in this situation we can see the real "Greater Good".
At the beginning we should look at a social situation in the magical Greater Britain at the beginning of Albus' struggle. The first half of 20th century the Wizarding Britain was ruled by magical gentry, that was a plutocratic society, ruled by small elite of wealthly people. I think this term is better than "aristocracy" because they don't have tittles but rather in ruling class were those with enough money, and "aristocracy" is too much similar to "lord stories genre". I know of course that in reality aristocracy and whatever ruling classes are they have to have money :) So how ancient and pure the Weasleys could be, they were too poor to have any political power, and their social standing was, as we see even in the books, very low. We know that ministers have names like Diggory, Crouch, the Blacks got orders of Merlin and the Malfoys were influential through their money.
We can see a society which was probably very stable. Just like any society where aren't any international/internal dangers and economy is stable, and society relatively peaceful. Ruled by rich gentry, so muggleborns, creatures and a magical lower class doesn't have much to say in politics. We can see that in 19th century muggle Britain. One of the reasons for social stability was that magical economy was very stable, contrary to muggle economy they don't have industrial revolution and later digital age. No new opportunities, no new possibilities of social advance. Only classical ways or inherited money. I think that someone with Hermione-like intelligence could also in that society achieved an upper middle class standing. There were some people who thought they they were unfair treatment, but their number too low for starting a violent struggle or political change anything.
The wizarding politics operated as a complex network of connections and patronage. Powerful individuals like Dumbledore or Lucius Malfoy formed their own groups on a base of patron-client system, they protected their retainers, and got their support on the fields where their clients were useful. Good examples like that could work are the Malfoys and the Crabbes and Goyles, we can see even in canon that those minor families with traditionally connected with the Malfoys for generations. Also Dumbledore's clients, friends and retainers formed during the wars a vigilante group called The Order of Phoenix. Arthur Weasley was Dumbledore's client, he got his job probably because Dumbledore's influence. His work in the Office of Misuse of Muggle Artifacts provided him with opportunity to raid houses of Dumbledore's enemies, like Lucius Malfoy and other conservative purebloods. During the war we can see that Dumbledore provided the Weasleys with additional security - housed them at Grimauld Place. Also Amos Diggory and Arthur Weasley were involved in a cover-up of an incident at Alastor Moody's place, who was a personal friend of Dumbledore. Moody could have been fined by the DMLE, if there had not been Diggory and Weasley's cover up. Dumbledore also had his clients but a word mole is better in more strategically places in the Ministry. Like in the Auror Office: Kingsley and Tonks. Kingsley was a prominent auror, even during an open conflict between Fudge and Dumbledore. Albus was probably informed about all confidential information shared with Kingleys.
Young Dumbledore dreamed about the Greater Good, I think that some aspects of Grindelwald greater good like wizard dominance over muggles might been appealing for him, because his family history. But finally we can see that he distanced from it. But I want to show his own understanding of the Greater Good. Albus developed that after friendship with Grindelwald and before the Grindelwaldian war. He thought that the Greater Good is a more equal society, with laws on benefit of muggleborns, creatures and lower class, from some reasons he disliked the gentry, and he could do anything to achieve his goal.
Now we jump straight ahead to the times after the Second War. What can we see? A different society, with a new social structure and new ruling elites. Creatures got privileges, muggleborns were praised and formerly lowstanding Weasley-clan became a main political power. Percy chief of the Transportation department, Potter married to Weasley a chief auror, Hermione Granger-Weasley probably chief of the DMLE and even the minister in the Cursed Child. Many old families destroyed. The Blacks gone extinct. The Malfoys just avoided the prison. Dumbledore's dream society!
His early attempts, when he was just a scholar, were ridiculed. I don't go into details. But after his duel against Grindelwald, when he was a celebrated national hero, this was his entrance to the ruling elite. He had already known that all political attempts are unproductive, even if he became the minister, he might become corrupted by power and bureaucracy was very idle and motionless, so even as the minister he couldn't do anything. I don't know when he took the chief-warlock tittle, which mostly I see as a ceremonial tittle without any real power. Probably he got the Chief-warlock after the Grindelwal War, but it is possible that well after the First Wizarding War.
During his young years Albus was looking, and realized that the real power to change, he might obtain if he can take control over education. He became a teacher with goal of being the headmaster later. As a national hero after Dippet resignation, Albus easily became the headmaster.
Dumbledore's ultimate conspiracy for the Greater Good.
He was working in the shadows, and he encouraged a development of things as he wanted. All with his dream about the new society. It wasn't easy, he wasn't totally sure about his success. He even sacrificed his life to it, although after being cursed by the Ring, he knew that he would die soon, so he orchestrated this sacrifice. He manipulated people, use their emotions. His school policy of favoritism of Gryffindors and antagonize of Slytherins was deliberate. Snape was an awful teacher a former DE, he was kept in the School to futher antagonize houses. Dumbledore knew that wizards were prone to kept their school feuds long, and that all propagate for adult society. And school houses were usually cultural groups, especially Gryffindor and Slytherin, where most kids of "light or dark" families went.
Caution: He didn't have a master plan and he didn't manipulated everyone and everything to turn exactly the way he did. He took advantage from new opportunities, and changed his plans when that was needed. His main goal was intact, but his actions changed over time and adapting to ever changing situations. He didn't plan at the beginning that there would be two wars and his death. Or that Tom Riddle and his little organization would became nearly victorious. Or that someday would be a prophecy and he would follow her. There was no a master plan, where he planed all his and enemies actions. Many times he was unsuccessful, and had to change plans and tried new actions. But he still manipulated and slowly things were going where he wanted.
I am not sure where Dumbledore created an idea to use Tom Riddle as his icebreaker who destroyed the old society, and after his defeat there would be possible to build a new brave world on the ruins. Rather not when he first meat Tom at the orphanage, it is too diabolical. I don't like exaggerated characters and conspiracies. I think that Albus was the first who saw that Tom Riddle was a ruthless murderer. Later, when Tom left school, Dumbledore started to think how to utilize that. Fina
And some years after Tom left the school. His organization the knight of Walpurgis (at the beginning a circle of friends) changed into a political group, which took on their banners the blood purity and became very extremist with this goal. At that time in 50s the fighting for the blood purity was absurd because the Gentry had power. I think that the early Knight of Walpurgis might be every attractive for younger sons of old families and members of slightly impoverished dark houses. They were the most prone to revolt against the status quo.
Dumbledore also worked through media, his media supporters worked to change common views on some social matters. So the most traditional part of the gentry and society started to be called "dark" which is clearly associated with being worse, and a progressive wing was called "light", which has good connotations. Also a media campaign and propaganda combat caused more insecurity in traditionalist circles which were more prone to support Voldemort against "aggressive mudbloods" and "blood traitors". This created so called a "climate of danger", polarizing propaganda, that people feel insecure and were more willing to join on of political sides. But not be very one sided. Albus still tried to change stuff politically also, but those his attempts were mixed if we are talking about his men in the top positions in the ministry. I mean the first muggleborn Nobby Leach minister in 60s, who was forced to resign by a clique led by Abraxas Malfoy. So we can see not all things were easy for him. Dumbledore knew that sweeping reforms weren't going to happen. Albus supported many laws which caused insecurity and anger in traditionalist circles, he counted that they would became angry and more prone to support Voldemort, even if those laws didn't get enough support, but quite often his more "delicate" laws were passed. So he still slowly worked for outlawing various branches of ancient magic, censoring knowledge, traditional rituals or "dark" artifacts, all of course "for the public safety" etc. Which was quite successful. And no-one even realized how much things had been changed.
Later the Knight of the Walpurgis changed into the Death Eaters and their policy changed into a full scale war, and massacres, which fully escalated in 1972. Dumbledore's policy to antagonizing and alienating Slytherins in the school made them more prone to join to the Death Eaters, also a death eater is more likely to dead before procreation or jailed or end as a society outcast, which was very deserved from Albus' point of view.
Dumbledore underestimated Tom Riddle, who was far more clever, powerful and smart than Albus thought, and that cost Dumbledore's plan greatly. The First War in early 70s broke because the Ministry started to get rid the Death Eaters, but that wouldn't go like the Ministry wanted. For Albus they were a leverage, for causing more chaos. It caused chaos in the government, society, and made a social situation unstable. Also the powerless incompetent ministry was more willing to seek for Dumbledore's help and this increase the power of his retainers and pawns called The Order of Phoenix. But he never dreamed that Tom Riddle might have been nearly successful. Barty Crouch and minister Bagnold were also very eager to fight against the Death Eaters, and their activity was one of the reasons why the Ministry didn't fall, and still was rather an effective fighting force, which could do a counter attack after the First Voldi's Fall. There might be a thing that Barty Jr was manipulated by Dumbledore to joining the Death Eaters to use later against his father. The Ministry was more effective under Crouch Sr. leadership, so less likely to seek his suport and allowing to infiltrate by the Order of Phoenix.
The War isolated many gentry families from the rest of society, because they were linked to the violent terrorists.
After the First War despite wounds caused by Voldemort, Dumbledore didn't success politically. The First War didn't go like he wanted. His goal wasn't achieved and it didn't seem to be any closer.
The Gentry firmly maintained the power, and even achieved re-integration of the formerly dark houses, as we can see with Lucius Malfoy's ascendancy. Dumbledore as an answer intensify his shady dealings, during the interwar period he manipulated society, media and education. Example he was the real force behind all "muggle protection acts" and raids on properties. Also, but still on the political scene was firmly opposed by the Gentry. A good example how he worked might be the Chamber of Secret. He enraged the gentry using Arthur Weasley "muggle protection act", and as a result Lucius Malfoy wasn't any more in the board of governors.
But in 80s he figured out one thing, to real change he had to got the new war. And he got. Not all in this war was like he wanted to be. The Light as supporters started to call antivoldemortian progressive stance was very close to defeat, but it was more caused by incompetency of his retainers when he died and it is in a big part Dumbledore's fault. He might have been a more suited to take advantage of the fall of ministry than his pawns, who clearly couldn't
There really was a miracle that they won, not the Death Eaters, but the final result was worth of all. His goal was totally achieved. He raised generations of light wizards who firmly believed in what he said. Example, Hermione under Dippet or Phineas-Nigelus Black would have been expelled after her attempt to sabotage all Hogwarts maintenance staff, but he allowed her activity.
Harry, the prophecy and the greater good.
I can explain Dumbledore obsession on Harry. I think that when Albus grew older he became more involved in mysticism and prophecies, the Deatlhy Hallows and similar stuff were parts of it. Which made him blind on some real problems and issues.
He firmly believed that Harry is the chosen one who was destined to kill Voldemort. But he made mistakes so he didn't properly trained Harry, but rather went into more mysticism and spiritual stuff about the self-sacrifice. He made a gravely mistake to not prepared his Order to fighting in real war and making Harry a self-sacrifice lamb. It might have cost him the final success if Voldemort had been more senile, and not incompetent madman after his reembodied. Although the cold calculation was never a strong side of Tom Riddle, who was too obsessed on own genius and pursuit for immortality, than a politics and his obsession grown bigger and bigger, at the begging he wasn't the same monster as at the end. He used to be a charismatic leader during his early years. Bu he became mad to the point that many of his supporters for the sake of their own safety dreamed how to kill him, and that's the reason why Cissa betrayed him.
So in Dumbledore's eyes and in real consequences the Second Wizarding War was more a war for changing a society and transfer the power and money to formerly disadvantage classes from previous owners. But it was such a bigger picture, and no-one other than Albus know about his conspiracies and ideas, that for all it was a war for the blood purity and to stopping genocide. Dumbledore was the most guilty person who caused this war, because he might have stopped Voldemort many times during his early years, or even didn't allow to raising him to the power. The Light supporters also didn't know why they really fought, but in their own eyes they fought against the real evil. Only some of them, like Hermione during the war had a picture of the equal society and social justice. Of course they had had already those views, and firmly believes, like Arthur Weasley. So when they took power they changed society in the ways, they firmly believed, were right. But the Light didn't created a one big political manifesto, their views were more distributed, a big basket which contains them. As Hermione with creature rights, Arthur with muggle protection, all with muggleborns support and so on. But Albus was the only one who had this big picture. So we can see a civil wars in Magical Britain as a social struggle, not only for blood purity. Both Voldemort and Dumbledore recruited people who believed that their social standings were unfair and felt insecure. So first he was responsible in a big part for destroying a social stability, which led to more violent society and wars, and finally to the destruction of the old society, where his supporters could achieve his goal of building the new society.
Despite his own death, and various errors, mistakes and obstacles Albus Dumbledore realized his life's goal. He wasn't an evil all-knowing dark lord, but a man who also many times were wrong. Was he evil or good? I cannot say. There is not good or evil in politics. But this very intelligent man was successful.
I hope that you like it. I try to developed a logical theory about manipulative!Dumbledore, which incorporated politics, society and gives a biggest picture than just "let's sacrifice Harry".