So, it's obviously hard to define what the Bay Area actually is. The SF to SJ corridor is one definition but that excludes East Bay, which is significant. Probably the best proxy is the SF-SJ-Oakland metro area, which seems to have a population of ~10 million people.
How many of those are tech workers? It's hard to say. Here's one estimate that suggests there were ~400k in each of SF and SJ a few years ago [1].
Some of those will be single or married to other tech workers. Others will have partners outside of tech. Some will have children. I'd say for every person in tech there's probably 1-1.5 other people as a back-of-the-envelope type calculation.
That puts the tech population at around 15-20%, which passes the sniff test (at least for me) and is significant. Obviously not all of those can vote (eg immigrants are represented highly in tech) but many can. So we're talking about a group that could wield a lot of political power.
But they just don't it seems. My personal view is that Norcal tech workers as a whole are just as self-serving as the NIMBYists they like to point the finger at. I suspect that a large number of them are the NIMBYists at this point.
[1]: https://www.bizjournals.com/sanjose/news/2020/09/16/san-jose...