I totally got the second job feeling.
I mean I love all the contributors - I do, but a few nights a week is fun, all of them is bad, when it starts to eat your Saturday, that's a steamroller.
There's reward, yes, but mostly there's a lot of people who (queue up the Sixth Sense voice) that WANT THINGS. I mean, everybody totally means well, they do... but so many people wanting so many things.
You could spent all your time just helping people who didn't read the docs, helping misunderstandings, restating the obvious, code review, website editing, so many things. And you have no time to do them all flawlessly, so you do them all the best you can, and get hammered on the things you couldn't be perfect on. Then you get into Catch-22 scenarios as the project grows and must please conflicting audiences.
Open source is really really really hard.
I think ones with very focused audiences (say, like, insect biology?) may have it easier - the more general purpose you are, the greater the demands from diverse audiences.
Programming languages may have it the hardest, I don't know.
Given, most people will probably think I succeeded at all of those things, but it also broke me in ways that would make me reconsider doing it that way again. Maybe everybody has energy to do it some, but ... it's rough.
There's so much more to it than just writing code too.