What makes you think that non-PhDs (except for the politically skilled) are more eligible for "meaty sizeable R&D type work" in Silicon Valley?

You may be right. I have no idea. I'm not in SF/SV. I will say that I'm not convinced that VC-istan has any real edge over the rest of the business world. It's just better at marketing itself.

FOMO is real but it's not only about geography. There are just very few companies that will pay for anything interesting. It's not like every 22-year-old in Silicon Valley gets to work on cutting-edge machine learning algorithms.

Ultimately, it's hard to get decent work. I don't know if moving to an otherwise overpriced location has decent ROI. I just don't have the data to answer that question.