[thousandautumns]

It might possible that most of the people in SF who own property have owned it for a long time. So for someone buying a house now, they would be paying a ton of money. If you bought the house more than 10 years ago, when prices were much lower, your mortgage would be much more reasonable and the monthly costs you would be paying would be less than what people are renting for currently.

Hence complaints of NIMBYism. The lack of new development in SF drives housing and therefore rental prices upwards, and so if you owned property before the bubble, you can now charge rent at the modern, high rental costs while paying a mortgage based on the lower pre-housing crisis prices. You could easily be pulling in thousands of dollars a month this way with a single rental property. So lots of people are now have a big incentive to fight against new development.