And a large part of that is going to be due to luck. I don't think it's all due to luck, however. I think there are certain qualities people have, and what people call a certain "chemistry" small groups of such people have.

Depending on how much luck you think is involved, those qualities can either be common or rare. I think they're becoming more rare in the Bay Area startup environment, as notoriety and money attract more people who are pale imitators of the outward forms of success. (Already, it's considered a great advantage to come as someone already part of a group.)

In this way, the Bay Area is no better or worse than many other locales where economic, cultural, or intellectual movements have cropped up. It's also, obviously, not a single monolithic "scene." But as the population of doppelgangers increases, there's the possibility that something akin to "herd immunity" may kick in, where small groups of people with the right qualities will find it difficult to meet. Already successful people will find it harder to "infect" other susceptible people with success.

I note that YC has decided to reduce their "class size."