I subscribe to two folk mags - the German 'Folker!', and the Scottish 'Living Tradition'. There are issues where I hardly read any item because it's outside my interests. There are others where I find a lot to interest me. Still, if I bought only those issues I'm interested in, and everybody else did the same, before long I'd be left without anything because the mags would fold.
Same with the folk music association I belong to. I'm not a musician, but I end up doing a lot of the work, e.g. bringing out a newsletter every two months, now starting to look after our homepage. You could ask what I get out of it apart form work, but that's not my viewpoint. One, I get together with people with interests similar to my own. You could say that through my work I buy my way into a community that wouod otherwise be fairly closed to me - musicians. Two, I do get personal satisfaction from the work I do. I know it's good and I know it's important to (at least some) other people. And three, what did Kennedy say? Don't ask what your country does for you - ask what you can do for your country. Put 'organisation' instead of 'country' and it fits. This attitude used to be called 'solidarity', I believe. It's gone out of fashion a bit.