People will be arguing over it forever (especially since people on different parts of the political spectrum want different answers to be true), but it's hard to say exactly what impact the high-tax/high-benefits regime had on Silicon Valley. As you imply, the taxes themselves are a negative, but some were spent on things directly relevant to Silicon Valley. One of the biggest was tons of university funding, especially up through the late-80s/early-90s (and especially compared to other states). In addition to the state generously funding UC Berkeley, Cal Poly, SJSU, etc. directly, Cal Grants used to pay full tuition for even private universities for CA high-school students above a certain academic threshhold, who chose to attend college within CA. That funneled lots of poor and lower-middle-class smart kids to in-state private universities, and indirectly subsidized the universities as well by having the state take on most of the need-based aid burden.