" much is limited supply coupled with high demand. "
No, it's just 'supply and demand' neither are 'high or low' necessarily.
SV has quite high wages, that's a huge driver of demand.
The residents of SV do not want to be like NY or Hong Kong, that is their choice. It's the choice many, many places make as well. Zurich, Paris, even London, they don't live in high rises.
The attractiveness of Cali in many ways is that it's not entirely flooded/urban like NYC.
There are not just arbitrary ways to create more homes, it has an effect on the situation.