After thinking about this some more, I can understand why he quit the band right after the record was done or why someone quits something in general right when it seems they've finally achieved it.
It's because achieving a fantasy essentially kills it, and the actual experience is a crude substitute for the one you had imagined. I don't know much about him or the band outside of what he has posted here, but I'd think it's a safe bet that having a band that played the kind of music he wanted, was marginally successful, and toured was a dream of his. I'd also wager that when he finally got there, it wasn't at all like he'd imagined it or as he'd wanted it to be. Everyone bashes the celebrities who get famous and are still miserable, and I understand why. There are few things as annoying as hearing someone with massive amounts of privilege try to tell a sob story. One the other hand, I'm certain being famous is not like we imagine it to be.
I think that's what happened with Cobain. He dreamed all his life of being a rock star, but when he got there he hated it...it wasn't at all what he wanted it to be. The death of that dream was so awful he decided death would be preferable, sadly.
Yeah, you know, that's probably the best thing anyone's said in this whole thread.
There was a band around here that I won't name that had achieved some really good acclaim and status in the hardcore scene (we're talking about basement shows, putting out vinyl, toured Europe, etc), and I guess that they'd hit a ceiling and had done everything that they'd set out to do. The bass player (the guy who ran their label and started the band) had refused to play the band's last show, and they had to find someone else. I didn't actually ask him why he refused to play the show, but sometimes you get so fed up with the whole situation (bandmates, financial status, etc) that it becomes hard to walk away with any sort of positive memories. Alot of bands break up under really bad circumstances, too.
There's other things like dealing with shitty promoters and club owners that won't pay you and whatnot. THAT really kills it. There's also a bunch of things that happen when you try to transition to other audiences and bigger audiences, when you're not just playing to the converts--people throwing shit and booing you off the stage and whatnot. I've seen some really, really morale killing shows for bands. When maybe things in the band aren't as good as they once were--your initial brotherhood--those types of things really test you as a band.