Next to drugs, the strongest predictor of imminent mental illness in a healthy person is a move caused by adverse economic circumstances (such as having to sell one's house, or move to a new city because there are no jobs). Moving scares people, especially after 25.
What the Bay Area and New York have in technology is an environment where (at least for now) people can bounce back from job loss (a likely eventual outcome of a startup) quickly and without having to move halfway across the country. I think this is a big motivator. Startups can thrive in the Bay Area because a person whose startup fails can find a good job shortly afterward, without having to move to another city.
Also, startup generation is a nonlinear function of the desire to launch them, because of the need to find co-founders and investors.
It's like that now, but when my SF startup failed in 2001 and I had to look for a job at the end of the bubble, it was extremely stressful --- and I'm guessing I had an easier time looking for jobs than most of my last-bubble cohort.
Continuing the same point: it is in fact not all that stressful finding tech jobs in any major metro area now. I'm in Chicago, we have offices in NYC (our HQ) and Mountain View, and it's hard to hire in all three places.
I'm sure there's a grain of truth in what you're saying, that SF can accumulate talent because talent moves there expecting the red-hot market in the area to mitigate risks. But things can turn quickly.
What the Bay Area and New York have in technology is an environment where (at least for now) people can bounce back from job loss (a likely eventual outcome of a startup) quickly and without having to move halfway across the country. I think this is a big motivator. Startups can thrive in the Bay Area because a person whose startup fails can find a good job shortly afterward, without having to move to another city.
Also, startup generation is a nonlinear function of the desire to launch them, because of the need to find co-founders and investors.