Not quite as famous and rich, but I think the top-level game designers are famous and rich enough, especially famous among the audience the would-be developers themselves are part of, to provide the motivation. Many people really want to be the next Will Wright, Peter Molyneux, John Carmack, Sid Meier, etc., even if that isn't quite the same level of fame as being the next Arnold Schwarzenegger. The bigger problem is that the odds of becoming the next any of those are really low (and nobody new has managed to claw up into that list in >10 years).