This is much of why I think the future is elsewhere. Not NYC, not the Valley. It's going to be somewhere where it's possible for a normal 40-year-old to have a career as a programmer (not a manager who occasionally codes) because it genuinely takes decades to become great at this stuff. Most of these "social" apps could be built by anyone, but if I needed a medical device, or an extremely high-performance numeric library, I'd rather the code be written by a seasoned gray-haired guy who understands technology at a deep level than by the sorts of people in charge at a lot of the startups where I've worked.
Sure if you work in finance you can earn more, but it's about funding a more lavish life-style than a necessity. Pretending anything else is insulting to the millions of families who are living on less.
Do startups generally pay below market? Yes. Is finance even more lucrative? Yes. But you certainly won't be "unemployed", as you suggested, if you don't work in finance.
List of tech companies in NYC: http://nytm.org/made-in-nyc/grid
Map of tech companies in NYC: http://mappedinny.com/