50k between Texas and SF isn't a difference, that's the whole point of cost of living adjustment. That being said, my rate is my rate. People happily pay it. I have access to the entire planet for my options, not just whoever happens to have an office within commuting distance from my house.

A large percentage of YC startups fail, so that's not really a metric that's useful. Basic market analysis will do: more potential employers = higher pay.