The property prices are largely driven by compensation increases. As long as there are more Apple/Google/Facebook engineers seeking houses than houses on the market, then there will be an incentive for housebuyers to bid up the price of available housing right up until it equals the extra money they earn from working at one of these Bay Area tech companies. Existing landowners will continue to capture basically all of these tech wage gains until the supply of housing exceeds the number of tech workers who want it.

The tech workers who are getting rich are the ones whose living situations resemble college students or service workers. They compete in the housing market for cheap apartment rentals with folks making maybe 1/5 as much, which holds down rents (well, sorta...rent is still insane, but only about 1/3 what a typical mortgage payment would be) and lets them bank the excess.