Also rich people that are willing to take a risk, and old people that stay relevant and up-to-date on technology.
I grew up in Boston and spent the first 4 years of my career there. The biggest problem the Boston startup scene has is that VCs won't fund you unless you're 40+, have a proven track record at an established local company, and can demonstrate a solid business model with LOIs or customer contracts in hand. Sounds reasonable, right? Except that Microsoft, Facebook, Reddit, DropBox, and YCombinator all started in Boston and left because none of them ticked the boxes needed to attract funding. I had lunch with Drew Houston right after he closed DropBox's Series A, when he was looking for employee #2. He said that immediately after presenting to Sequoia, the whole office had checked out the product and he had a term sheet within a week; meanwhile the Boston VCs they presented to (despite knowing Drew since childhood) had hemmed and hawed and said "We need more data".
These are the kind of cultural differences that aren't easily papered over with policy. They're also why the Midwest and the South struggle to attract and keep startup ecosystems. I suspect that many of the problems in California (over-regulation, direct democracy, laissez-faire overlooking of social problems like homelessness & crime, the tendency for everyone to jump on the next bubble) are actually the flip sides of the cultural attributes that make it great, which is an extreme openness to new experiences and a willingness to take a chance on new ideas.