It's just that if you ask anyone around here "Would you like $5 million now, or a chance at an unknown percentage of somewhere between $5 billion and $0 in 10 years?", even the entrepreneurial types are going to take that first one most of the time.
Interesting thought: $5million is totally "f you" money around here in the Midwest; that's retire instantly for a fairly nice lifestyle, plus a quite healthy buffer. In Silicon Valley, that's still nothing to sneeze at, but it'll certainly seem like a lot less; a lot more people for your monkey brain to see around you that are still richer, a lot of single houses that can soak up that entire fortune and more, etc. You could retire instantly, but you'll have a lot more pulling you away. I wonder if that has any influence in the results?
And of course there's also the fact that anyone who won't settle for anything less than the % at billions above will move to Silicon Valley. There's a lot of places in the world where you can make a successful startup, sometimes HN even has articles pointing that out, but there's not very many places you can get the rocket-powered VC capital to either grow a unicorn horn or die trying.
Besides, as the article said, $10M is more than enough to look down on your neighbors for the rest of your life, what more benefit could $10B give you?