Tony wasn't what everyone thought he was. Sure, he was selfish, he was loud and disrespectful he won't deny it, but one thing to never ever mistake him for is stupid. The one thing that he would never be is stupid.
He knew what people thought about him, that he was a cocky, arrogant playboy with enough money to last a lifetime. Make that a hundred lifetimes. He didn't care what they thought of him. In fact he encouraged it. Once people thought they knew the real you all, their thoughts and opinions of you were based around what they thought they knew. All he had to do was put on the show that people wanted, sprinkle a bit of magic and charm here and there, and then suddenly you had the audience eating out of the palm of your hands and looking everywhere except where they should.
But there were always the few that saw through his facade. That peered behind the curtain and saw a glimpse of what was underneath. Who thought they understood how the magic behind the trick worked, that they knew what the man behind the name Tony Stark was. They would label him, try break him down bit by bit thinking they knew how he worked, how he was put together but in the end like everyone else they always ended up constantly surprised when there turned out to be something more. Something more they had missed, misplaced and that was unknown until the magician purposely brought it into the light. Onto the centre stage. Only noticeable to those who looked.
And that was why Tony Stark is and will always be the most dangerous of the avengers. Because he's wild and uncontrollable. Unpredictable and destructive like an oncoming storm. He's chaos and destruction in nature's full form. He isn't super-strong, nor super-fast. He is not the best with weapons through he has his fair amount of knowledge due to his past activities. He cannot turn into a big green indestructible monster nor does he wield a hammer and have the abilities to control thunder. He is not the best marksman in the word or the most feared assassin. But the one thing he does have is his mind.
His mind is his greatest asset.
With nort but his mind combined with his knowledge he invented and created the first iron man suit while being held captive in Afghanistan in cave with little resources. And used it to escape the hell he was being held in.
Not only is Tony Stark dangerous because of his mind but also because of the power he has publicly and politically. He is well known all over the world and is one of the richest men on earth. He has resources and connections everywhere. But yet everyone seems to forget that. They seem to forget that Iron Man and Tony Stark are the same person yet everyone refers to them as is they're are not. They approve and speak highly of Iron Man. The hero. Their children's role model. Yet they disprove and talk about Tony Stark as if he is nothing but a spoilt, arrogant play-boy not even mentioning that he just so happened to have saved hundreds of lives and who had built what could be the most dangerous weapon in human history. So far.
No one knew the real Tony. Not Rhodey. Not even Pepper. Oh of course she has seen glimpses over the long period of time she has worked for him, but it was only just a peek under what he had hidden underneath his facade. And it scared her. Not for her own sake, no but for the poor souls who underestimated him. And there were many but she couldn't do anything. It was too late. The darkness had festered for too long and now there was little else left. Nothing could bring him back. He'd become jaded and bitter. Seeing the bad side of the world will do that to you. The weapons he'd made protected his country but at a price. He was forced to stand near the flames and it was only a matter of time before he had gotten burnt. As the saying goes "he who fights with monsters should see to it that he himself does not become a monster. As when you gaze long into the abyss, the abyss will glaze back into you."