There is a huge difference in rent between the different parts of SV. You have to pay rent, but it doesn't have to be Palo Alto rent.
None of this means that there aren't valid reasons for staying here; even giving up a fairly significant portion of my income as rent leaves me with more money than I'd likely have after rent if I had a comparable job in Tampa, assuming I could even find one. But I don't think this is a sustainable situation for the region. The nanny in the "This is your life in SV" satire, and other people in her salary range (or under it), are on the cusp of being pushed out of the area entirely.