[birken]

You always need somewhere to live, so you can only "sell high" if that means you can "buy low" somewhere else. If all bay area houses go up 10%, then you haven't actually gained anything assuming you still want to live in the bay area.

You also lose at least 5-6% of the value of real estate every time you buy or sell. So given that buying/selling real estate is complicated and expensive, and moving is complicated and expensive, for the vast majority of people, the value of the house going up and down _in the short term_ is mostly irrelevant.