SV is also great for the non-compete (it's a California thing but shines especially bright in the Valley), formal mentoring with a strong presence from Stanford

SV is also great for the non-compete (it's a California thing but shines especially bright in the Valley), formal mentoring with a strong presence from Stanford and incubators like YC and informal mentoring where the younger generations are inspired by what was built by the previous ones. And the lack of stigma for failing plus having a world class city right at the door. Very few places can replicate that.