We do need more people in San Francisco. It's one of the most productive cities in the world.

But there's plenty of space there already: upwards. It's just illegal to use.

GDP per capita is a poor measure of productivity, and doesn't consider externalities.

SF is pretty good at producing emotionally manipulative adtech to opt every Internet and smartphone user into a global panopticon, and also quite prolific at social media that turns our lives into perpetually distracting hedonic treadmills.

Time will tell whether the "productivity" of SF was a net benefit to Civilization.

I'm just looking at people making good money for themselves (from high wages), and paying taxes for the benefit for the rest of the country.

A million dollars will buy a few square feet of land in San Francisco. In the middle of nowhere it can buy a square mile. Humans might prefer the former, but most other species would prefer the latter.

Unfortunately habitats are not fungible. A square mile of dry land is unlikely to be suitable for the species which live in the wetlands of a tidal estuary.

Why not make some additional wetlands too? Land is so expensive in SF that doubling the construction cost of this project won't really change anything.

And industrial wasteland is suitable for neither.