And those that bought in the 1980s or earlier and stayed, or inherited their parents' house.
If you want to move close to, but not in Silicon Valley, try looking farther away but in-state. And watch taxes too. State income tax is high, as is sales tax and gas tax. Property tax is relatively low.
Contemplate eastern Contra Costa County or Livermore. The houses are half the price there. BART can get you to Fremont, which is close to San Jose. The Bay Area just doesn't get that cold. You won't need snow shovels or much of a winter wardrobe. CA lifestyle is much more out-of-the-house oriented, so you don't need as much house. Heck, if you want to have a family get together and the house is too small, then have a barbecue. Just have a covered patio if it rains in the winter. My parents had 40 people at the house for a surprised birthday party for my dad. She hid the party food at the neighbors house. It was December. Our house had 1300 sq. ft. But the covered patio made it possible.
Or move farther out. My aunt's property in the Sierra foothills went for 48K last year, including a double wide (that needed repair) which the buyer junked.