In NY people try to maintain monopolies of information. One place that applies to is a very restrictive work for hire doctrine. If you have a job in NYC, by default everything you create belongs to your employer. Even if it was done at home on your equipment. In California that particular right is one that remains yours and cannot be lost (unless what you do relates to your employer's business).
The result is that in California it is common for people to have a day job and work on the side on a startup. You almost never see the side startup in NY. Furthermore if you do see it, those startups can be squashed in an instant when the employer finds out about it. I've seen it happen. Not pretty. (The same thing can happen, and does from time to time, with open source projects. However it happens less often because there are fewer cases where someone wants to leave their day job for their open source project than cases where they want to leave their day job for their startup.)
That nasty little dynamic is a constant hidden drag on NY. Nobody knows how many good ideas got squashed and never saw the light of day...