In practice I don't know how big 996 is but a lot of people are putting in a lot of effort and excitement into their current startups. It's not too dissimilar to SF in the social network and early gig economy days, along with all the posturing about working long hours (the motto then was "work hard play hard") even when nobody is actually working the hours they say.

But the energy is a bit infectious. I'm happy to see SF on the rise again.

Far, far bigger than any other US city. Why? IMO with AI it's basically an arms-race mentality and a lot of the startups/labs here are grinding 24/7 to snap up the industries before legacy businesses realize what's happening. It's a lot easier to feel that energy/pressure when everyone around you is doing the same thing, vs in NYC or wherever where everyone is out enjoying their weekends.

It was a ghost town last time I was there about 6 months ago. You could walk down the middle of Market St at 9am on a weekday because its so empty. The only time I ever saw SF as empty was 9/11/01.