- The dot-com bubble in the early 2000s left a bad hangover, but also built up a set of young people with tech experience and lots of ideas who enjoyed working for non-traditional companies
- Those people often went to go start their own companies (disclaimer: I am one of those people). In the early 2000s, though, it was tough to find top tier VCs who were willing to invest in NYC. I remember in 2004 meeting a VC who said they would love to invest at a great valuation if we committed to moving the company to boston or the bay area
- Consequently, the selection criteria for NYC companies who got VC funding were often those with strong revenue streams, which led towards less sexy, less "moonshot" companies to those that sold products for actual money.
- The other driving criteria was those where geography was an advantage, which also led to financial services/enterprises or advertising
- As those businesses grew, expanded, raised more capital, it drove more VC money to NYC, which created more air in the room for more startups.
It's really a very straightforward evolution. As far as why Seattle "flails", I think it's even simpler - Seattle has a population of 650k people. A handful of large companies, Microsoft, Amazon, etc. can take a huge percentage of the engineering talent, and there's neither the educational base of graduates that the bay area or boston offers nor NYC's base of large corporations to sell to.