Intense and selfish desire for something, esp. wealth, power, or food.
There is no member of the team that Spencer would describe as greedy. They gave their lives every day to keep people safe. Hotch gave up his marriage and his son. Prentiss gave up her chance at being a mother. J.J. gave up her sense of safety. Garcia gave up her naivety. Derek gave up his secrets. Rossi gave up his relaxation. And Spencer- Well, he'd given up his mother.
But when he really thinks about it, he would consider his self the most greedy member. He is greedy with their time. He can't get enough of it. He is always needing something from them. Their help, their attention. He gets hurt more than any other member on the team. He's been kidnapped more than any other member on the team. He doesn't drive and is regularly given rides.
After Maeve dies he closes his self off. There is nothing left in the world that he desires. There is nothing else that dictates that his living is good. He realizes this when he shuts himself in. He'd gone to the team with nothing and they'd given it their all. They had not only found Maeve, but found her stalker. They'd saved Spencer but they hadn't been able to save Maeve.
And now? Well, now, despite them giving everything they had when he needed them, he can give nothing back now. Whether they need anything or not. There is nothing of him to give. And that is greedy. All they want is him and he refuses them even that. He takes their help and throws it aside in order to lick his wounds in private.
He is greedy. He is a sinner. He wishes now, for the first time since it happened, that Raphael would have killed him in that shed.
So when it wears down and he's out of tears he allows them inside to pick up the piece he let drop. The team rebuilds his shelves and the walls that protect his heart. He accepts their cooing and coddling. He releases all responsibility for that section of his life and greedily allows them control.
It's love. All he's greedy for in the world consist of that one word. Take his money, take his books, take his intelligence... But if you take his love; If you take from him those that truely love him, then take his life. Take his life for there will no longer be any use of it.