>>214275462 (OP)
During WW2 shitloads of infrastructure was built in California to support the Pacific War. And tons of highly skilled workers, experts, and intellectuals were moved out there to support it as well.
After WW2 a lot of those people and most of that money just stayed around. The US government pumped a bunch of money into the Californian educational system for example. ARPA, later DARPA, operated heavily out of almost military run colleges in California.
Silicon Valley taking off then took this a step further. There was a competition here, between Massachusetts, Upstate New York, and California, about which would hold the future of the US tech industry. And for a variety of reasons, California won.
Today all of that is still in play and is something that they've inherited.