So many comments in this thread assume that people live in SF/NY purely for the money and access to jobs. I think people are missing the point that people actual like living in these places too and are willing to pay a premium it.

I live in New York and like living here. I understand the cost of living here is high, but I also know that there are few places that can offer the lifestyle New York can. Given the option to keep most of my salary and relocate to a lower cost of living city, I think I’d stay in New York.