alt Hacker NewsSf is 7 square miles. You can cut a swath out of that size out of other cities and find that density. Possibly more density. Koreatown in LA has like 45k people a square mile, over twice as dense as sf. Several other areas there clock in at a higher density too. Really you need to consider it as just a region in the greater Bay Area metro region. And given its prominence in position as a transit hub with billions invested over decades in just that effort, it makes sense to add density there.
Yes, SF is only 7 square miles, so already you don't have much to work with. The Bay Area is the 4th most populated metro in the USA. So still not as dense as NY or even LA, but still denser than the vast majority of places in the USA.
1. 2,251.1/sq mi Los Angeles-Long Beach-Santa Ana, CA / 12,828,837 2. 2,156.5/sq mi New York-Northern New Jersey-Long Island, NY-NJ-PA / 19,865,045 3. 1,614.4/sq mi Trenton-Ewing, NJ / 369,526 4. 1,303.6/sq mi San Francisco-Oakland-Fremont, CA / 4,466,251
Bay Area density fairly well correlates to SF's density, actually (yes, not as dense, but neither are the metros around the other dense cities).
More housing is always great, but I think it is really idealistic to think that building more housing in a hot area is going to bring prices down much, if at all. Literally, anywhere in the world, that simply doesn't happen. At best, we get a place like Berlin that has a nice economic bust that brings housing prices down for awhile (and then they start ticking up again as the economy improves), or Tokyo, where a country-wide baby bust coupled with anemic local wages and a huge 1980s housing boom hang over, keeps things reasonably priced.