Anyhow, the thing: There are a lot of instruments in the house and kinds of music that I'm interested in playing, and I'm not sure where to best direct my attention and time and monkey. This would not be a big problem except that I am renting the cello (although I've got money from my double bass that was earmarked for a cello), so I feel kind of silly not playing it regularly. On the other hand taking it back to the Sound Post makes it feel like a decision to give it up.
On the other hand, as much as I've enjoyed going from nothing to Bach, the folk music world has a lot of appeal for me as well. I'm decent on the Irish flute and tinwhistle, and I think I could get to "pretty good" with regular practice. And then there's the guitar and tiny-accordion and bodhran*.
So I'm not sure what to do! It was nice to pick up the cello after years of not playing the bass I owned; it sort of felt like I was going back to classical music on my own terms after failing to do it on other people's terms back in school. But I think I set my sights a little too high on how dedicated I was going to be to getting good, and there's something about the amateur/professional divide and the "adult amateur" classical world and conservatory exams I'm not sure about.
Folk and Irish music on the other hand is for the most part a big welcoming community, and one that I enjoy being part of. You can't make a living with it unless you luck out, unlike the classical world, so you don't have the divide, and it's not quite as... classist? as the classical music world. (Never mind Comhaltas for now.)
(Of course, if I already owned the cello I'd be fine: it can sit as long as it needs to until I'm ready to play more. But going out and buying a cello at this point to solve that problem doesn't seem like a good plan.)
But like nyxie points out, I tend to get bored with things quickly -- although I wouldn't so much call it boredom with the current thing as it is getting interested in the next thing. And I feel silly putting a year of hard work into the cello only to stop, although perhaps part of the problem was that I put a year of hard work in instead of a year of fun.
I don't know how other multi-instrumentalists do it, either, although I think part of it is "get really good before adulthood and then maintain that".
* which I'd have to get reskinned or replaced; the weather won over the goat at some point there.