The short answer is because we were living in New York when we started Hacker School.

As to why we were living in New York, I can only answer for myself, but here you go: I grew up here (city and suburbs), most of my family still lives in the area, my friends live here, and I love the energy of the city. It feels like home.

Presumably because he's based there.

If he wanted help/sponsorship running SF or Seattle, I'm sure he could find it, though.

I actually think Hawaii or Thailand would work -- you could get a few cheap house rentals on the big island, with minimal distractions, and do it there.

Cost of ticket would offset cheap housing probably. Any small midwest town would work and be much easier to reach.

Yeah, but the real cost, IMO, is the cost of the "residents". I think one could convince 1-10 great people to take a working vacation in Hawaii for a while for $x. I'd expect 10x for St. Louis. (NYC, Seattle, or SF would have local people, so it would be a different thing...more part-time, but they could continue going to day job)

SF to Hawaii flights are $300 r/t. If it were in a place like Boulder or Utah, you might be able to get local companies/VCs to sponsor it, though.

An issue with small midwestern towns is that there is not usually temporary housing available, unless it's a college town.