>"Why is that? What's wrong with SF for dating? (just curious)"
Where to begin?
The tech industry is massively skewed towards male, so right off the bat your odds of meeting someone in your work life is near nil. Then, with the complete lack of affordable housing, there's no such thing as just being a single 20-something living independently and supporting yourself on a non-tech salary. Bare minimum subsistence income is about $80k. So that filters out the vast majority of women who are in non-tech careers and simply cannot afford to move there.
At that point you're basically left with the lucky few locals who have parents that bought houses in the 80s/90s and live with them rent free, or the unicorn types who make enough to live in SF independently.
From that vanishingly small pool of women, you're now competing with the guys who made startup money or have the $300k+ FAANG gigs and can afford luxury vacations, nice condos, BMWs, etc.
An average dude doesn't stand a chance.