hackNYer here. 4 days after hackNY is over, and I went back home to hang out with old folks, you realize how important and why living with other fellows is definitely the key, always doing something cool, learning, or teaching other people. That's why it's unbeatable.
The fact that it's in NYC where the startup scene is still far ahead from what its like in SF also adds to it, because you are sort of bound to hang out with other fellows as you are (likely) coming from other city, and since it is NOT SV/SF you don't know many (if any) people working in tech there.