A buddy of mine years ago did a sports-coaching related start-up in Washington, DC. It was a cool idea targeted at high school and college football teams. He

A buddy of mine years ago did a sports-coaching related start-up in Washington, DC. It was a cool idea targeted at high school and college football teams. He wanted to stay in DC, and had the talent he wanted there. His app was high-quality, and he ended up getting an investment from a VC. The VC was based in SF. My buddy didn't want to move there, but the VC made the investment contingent on him relocating to SF, because that's where the VC lived. He made the move. He immediately noticed that he had to pay far more for people who weren't any more productive or talented than what he had in DC. His biggest gripe was that the turnover was a lot higher, and he was often getting people who seemed to have lower aptitude for their roles. Apparently, VC's requiring relocation to SF is a common thing, and I suspect that it's part of the reason so much is concentrated there.