Good points, Tom. I'm firmly in the third category "happy to do a bit of both". While I enjoy performing, I also love listening both to established artists I've seen before, and new ones I haven't. I regularly go to concert clubs (and concerts in theatres etc.) as well as doing floor spots, joining in sessions and singarounds at other clubs. I know plenty of people in the first category "only want to listen" who are happy to support clubs week in out (at concert type venues and singarounds/sessions/locals nights), but they don't perform (except perhaps singing along with choruses, etc.) - maybe they aren't talented enough, or are too shy, or whatever. That's OK, it's what they are happy doing and we need them.

But I find it difficult to imagine why anyone would be in the third category, who only want to perform but not listen. It just seems strange to me, but as people have said above, maybe these are people with big egos who don't think anyone else could be worth listening to. But if they really are that good, why aren't they doing gigs in the concert clubs? And I assume they must write all their own material too.