>How is it that he was so successful and how did apple become the behemoth it is today if the man at the wheel was so insufferable?

Unlike the other commenters, I don't think the answer is vision, tho it certainly plays a part.

The reason people kept working with him is because when he wanted to he could be devastatingly charming. He was one of those people that can make you feel like what you have to say is the most important thing in the world. He was so good they coined a whole piece of slang just to describe him: http://en.wikipedia.org/wiki/Reality_distortion_field