Gentrification is a good thing. You can't do all of the liberal shit San Francisco's municipal government wants to do without a bunch of "2%" types whose taxes can bankroll the whole endeavor. You lose your tax base, and you turn into Detroit or Camden, NJ, and then its game over. If you're a municipal government, 90% of your energies should be spent figuring out how to get businesses and wealthier people to move into and stay in your city. Without the tax base, your great ideas for everything else are totally irrelevant.