Tangentially, lots of folks complain about high CA taxes, but these taxes largely go towards local projects and paying local salaries (unlike Federal taxes). These projects and jobs are direct stimulus to the economy and also provide a large potential customer base to startups. This is likely playing a bigger role in the startup ecosystem than most people realize.
On a more specific and personal anecdote, the green/clean energy sector is heavily based in CA because CA was an early mover in climate change energy policy and regulation. These policies started in the 70's, and the long slow growth of the industry that they enabled may be the primary reason that the US is even remotely in a position to try and tackle climate change (still a long way to go though). It takes a certain cultural and political climate to embrace these types of things, especially when the potential return on investment is on such long timescales.