That's because creation of new housing is highly restricted in Silicon Valley because of high regulation and very restrictive zoning laws. And additionally all

That's because creation of new housing is highly restricted in Silicon Valley because of high regulation and very restrictive zoning laws. And additionally all the money that would be going to the low income is getting sucked out by the continuous raising of the minimum wage, greatly restricting the size of the labor market at the low end resulting in higher unemployment.