I think this very much depends on your own attitude. Sure, there are assholes who will say things about how useless is your project and how they hate you for it

I think this very much depends on your own attitude. Sure, there are assholes who will say things about how useless is your project and how they hate you for it, but this is not the norm in open source. And it's definitely not the norm when it comes to developers, not users. I have worked with various people in open source, including some that are known to be "not good at dealing with people", but I never had a serious problem with them. In fact, just a few weeks ago I had a wonderful experience contributing a patch to cairo. You meet a new person and you are working together with the goal of the best quality code. I was not doing much open source development for some time and it was amazing how great it felt again.