[jepler]

How does anyone learn anything?

I'm no Bill Gates, but I am a college drop-out who makes a living writing software.

I think there are a couple of things that came together for me: Access to computers for the purposes of programming (including in school settings from about age 8 onwards), interest in them, encouragement from family, and enough college level classwork in CS to get a good theoretical grounding. When I left college, it was half because I was too poor a student to buckle down and complete my coursework, and half because I'd found a job at a local software company that already paid pretty well.

Compare to Gates, whose wikipedia article states that he started programming at 13 in a prep school and soon formed a "programmers club" with the goal to make money; he "took leave from" Harvard to found Microsoft and never returned.

The other thing it's important to remember about whoever you think of as a 'big name' is that they are by definition extreme outliers. For each Gates, are there 100 people whose company failed, and they either returned to school or left the discipline entirely? Are there 1000? On the other hand, there are also a lot who took a similar road and arrived not at worldwide fame and extreme personal wealth but at contentment in their work and comfort in their lives.