40 seems like about the time you've got enough experience under your belt to build something extraordinary and enough comfort with money (or access to money) to realize your vision.
Steve Jobs would be an interesting one for this list.
He didn't change digital production history until he was 40 years old w/Toy Story in 1995.
He didn't return to Apple until 1997 and turn it into the world's largest consumer electronic's business.
Everything before that was marginal by comparison.
Apple up to the Mac is practically the prototype of the Silicon Valley young-founders-in-a-garage startup. To depict Steve Jobs as a late bloomer who did nothing big before 40 is silly.
Steve Jobs would be an interesting one for this list.
He didn't change digital production history until he was 40 years old w/Toy Story in 1995.
He didn't return to Apple until 1997 and turn it into the world's largest consumer electronic's business.
Everything before that was marginal by comparison.