I understand that Ycombinator works to help non-profit startups - but how does the relationship between investors differ in a non-profit vs a traditional for-profit company?
Err... I think they don't. Not sure they're investors, either, but 'benefactors', contributors, donors or something else. When you give money to a non-profit, I think you're doing so under the assumption that they're not going to give it back, plus a nice return.
That makes sense to me - are the contributions then able to be considered tax deductable? I guess that would depend on the type of non-profit?
If it's a non-profit, I think so, up to some level. Probably best to ask an accountant for the details though.