Or an article from this year listing LA as the 3rd-best place, after Atlanta and Vancouver, for moviemakers to live: https://www.moviemaker.com/archives/best_of/best-places-to-l...
One important factor at work here is the Internet. Effects companies, for example, are all over the place, including London, New Zealand, Vancouver, LA, and even here in San Francisco. Big movies will often use multiple companies, something that would have been very challenging 30 years ago.
Silicon Valley does have capital and talent. But it's not like that capital is in doubloons in a vault. It's purely digital. A big reason it's not more mobile is that VCs wouldn't deign to stop in a flyover state. Talent isn't quite as mobile, but a) advances in technology mean talent is less necessary, and b) the rise in remote work means the location of talent is less and less meaningful.