He's an actor, trying to further his career. I have to agree, at first, I actually liked and could respect Buddha: he seemed like he was honestly interested in New York and the way he stood up for his beliefs and the way he defended other people in the house was honestly admirable.
Then he came back. And I have to agree with another poster: he got too cocky. Fighting is like the zero tolerance thing on these shows, yet she liked him enough to bring him back in the house. Tailor Made, the other person to make a big impact, was in her dog house and he knew (it wasn't hard to tell) that was big competition. He pretty much walked in with the attitude that he had the competition on lock.
But the arrogent, slightly vain attitude was always there: when he got eliminated, he said that he felt bad because he felt that New York was missing out on the chance to be with him, not the other way around. Hell Date speaks for itself (I'm beginning to think that's his real attitude cause he did it on ILNY too.) and just the way he carries on with Tiffany: like they're already going out and he tries to control her.
He just gave off the vibe that he wasn't really there for Tiffany, just there to be the star of the show and cause drama. That's probably the only real reason she kept him so long, unless they were sleeping together and he's...very good at that. It's sad, but if one of them could get a spin-off, she'd probably give it to him because of the impact they had together and VH1 probably already sees dollar signs and ratings.
(I think it would have been more intersting if she'd picked him and then we watched the relationship. I could only imagine...)
Which is sad since Punk is more deserving than he is.