From a less cynical perspective, the fact of the matter is that compared to anywhere I'm aware of, the Bay Area has a much stronger culture of entrepreneurs assisting each other. There's a much stronger culture of what could perhaps be framed as mentorship, with a large population of people who have been in the game for a long time and are still engaged as founders, executives, or investors. It's also probably one of the few places where there's a widespread acceptance that innovation means experimenting with risky business models without being forced to constantly focus on short-term revenue.
From a more cynical perspective, in many cases for younger or newer founders, this means it's easier to climb the social ladder and be in the "tech entrepreneur" scene. It feels exciting and the money flowing around between young people (something that doesn't exist everywhere) makes everything seem more real than it is. I also think it's far easier to inflate the value of companies here for a variety of reasons.