Well, of course, the richest people will all come from the high-risk high-reward pool. But the expected value of doing a startup could easily be lower than working in an investment bank.

If one startup in five "succeeds" and the average return is 5M after 5 years of work, then the expected annual "salary" is 200K. Not a completely unreasonable figure for investment banking (I have no clue what the real numbers are. Plus, not everyone can work in wall street or do a startup)

If that's the case, then a startup would be similar to a lottery ticket. Do it for the thrill, do it for the experience, but don't do it for the money.