If people are choosing to live in the Bay Area and spend all their money on COL expenses, that does not mean they are not wealthy. It just means they are choosing to spend all their wealth to stay there. Believe me, those of us who live a state or two east of there see plenty of people who have left after a few years of paying on those jumbo loans, and the equity from those homes sets them up quite nicely in another place.
People who own homes in the Bay Area do not have massive disposable income. But they do have wealth.