You didn't mention Bill Gates, but he is often cited as an example of a successful college dropout. That is more myth than fact. This is what Bill Gates said about his college education at Harvard:
It is strange to call me a college drop out in all but the most literal sense. I went for three years and took enough courses to graduate...So I am kind of a failure as a drop out.
One theory that I've read about, especially in the context of the electronic payments industry, is that college drop outs have only two choices: get a low-paying job, or risk the realities of forming a new business. Necessity forces them into entrepreneurship.