I've seen "low" rents there, but you get to live in a rough looking neighborhood and its not very clean or safe.
To be fair, if you're making 170-240k base you can easily afford 3-4k per month rent to live in a nicer building. People who are in relationships can stretch this even further, not to mention the RSUs/options.
Also, people live all the way down to SJ and then up the east bay. Rents in SJ are like 2500/mo for a single bedroom in a newer building, but its not that great of an area tbh. In mid-peninsula its comparable to SF rents because it is really nice, safe, and you get a lot more families. There are no homeless and barely any crime there, and SF is just 20-30 min away.