That those business are concentrated in such a small area would seem to suggest it's not because of California, but in spite of it. Concentration begets concentration, so when you have a preexisting concentration of tech companies, that concentration will continue almost regardless of the local or statewide political environment.

Even still, why aren't said companies concentrated in other states ?

It kind of makes sense they're geographically pretty close?

If you were going to start a tech company in 2010, why wouldn't you build near other campuses ? Hiring etc would be so much easier. You'd be at a disadvantage to be in another part of California?

Seems like your arguing that Silicon Valley does capitalism better then anywhere else in the world. If it were a California thing then you would expect similar results in more than one city within the state.

Los Angelas has a tremendous concentration of the film industry, so its not just one city.