Jobs will go to extremes for his sense of justice. He could have stayed at Apple the first time, but he quit instead to make a new company that did what he felt he ought to do.
No, I'm not. I got a Mac about 6 months ago, and while I read things I find interesting about the company, I don't go out of my way to read biographies and the like. So from what I'd read, Jobs was demoted and he chose to quit rather than stay at his position.
You don't have to go out of your way to read biographies. In Jobs' Stanford commencement speech, discussed and linked many times here on HN, he talks about being "fired" from Apple. He also discusses it in Cringely's "Triumph of the Nerds" documentary. Given that Jobs himself publicly acknowledges that he was fired, I'd be interested to know what it is you read that claims otherwise.
But then our visions of the future began to diverge and eventually we had a falling out. When we did, our Board of Directors sided with him. So at 30 I was out. And very publicly out. What had been the focus of my entire adult life was gone, and it was devastating.
That I always assumed meant he left for something else, but rereading I can see that he does specifically say fired. Huh! I don't know where I got the impression that he left voluntarily, though it's one that I've had for a while now.