I don't work in tech. Dietary supplement manufacturing in North Dakota
As someone who has been in FAANG quite a while, I can afford a house. But in Silicon Valley I can only look at 50-60 year old neighborhoods where the original owners were postal workers, grocery store managers, truck drivers. People that today couldn't qualify for a fraction of the necessary mortgage. This sure doesn't feel like economic progress.
Agglomeration effects. Those postal workers could certainly afford homes elsewhere, but the economic value of having lots of tech workers together in the same place is higher than the marginal (in the economic sense!) postal worker living here.