It does seem to me like Ben's being taken to the Others to save him is what made him evil. If Jack had saved him, he wouldn't have been. But with what he knew about Ben, he thought he was doing the opposite. Really, there is no way Jack would have saved Ben. Which is why I think if he had, things would have been different. That is to say, the whole series would have been different. But it seems like Jack's indifference to helping Ben is what created Evil Ben. Jack is the central figure in the show, and now we know why. I guess the show will end when Jack realizes he was a jackass and that if he'd fixed Ben up, the plane crash, Dharma being killed, everything; none of it would have happened. It all comes back to Jack. Ben might be responsible for a lot, but Jack made him that way.