Huge tech community, almost perfect weather (it's not San Diego, but it's close), fairly liberal politics, diverse culture (means tons of interesting and fun cultural activities, and lots of interesting places to eat that you don't get somewhere that isn't a larger city).
You may not agree with or value those things, but a lot of tech people do.
San Francisco weather is not even remotely close to San Diego... It's significantly colder, foggier and windier, particularly in the summer. The high/low in June/July/August is comparable to December/January/February in San Diego.
Nope. Tech workers trend more liberal, more well-travelled and so on (I'm sure you can find negative ways to frame the differences as well). The cultural differences are real.
Rather, tech workers in San Francisco trend more liberal. This is because the city generally trends liberal; it's not specific to tech workers. Outside of that bubble, tech workers are the same as anyone else.
The largest single employer of tech workers in the world is probably the US military, and those tech workers definitely don't trend liberal.
You may not agree with or value those things, but a lot of tech people do.