For me, it was the realization that I had been doing the same thing over and over for several years, had no prospects for change, got no special respect for my skills and experience, and was being paid much less than the incompetents wise code I was being asked to fix. Share what I know? Learn at work? Nope.

Sure, all of the above is my fault. But once you've dug the hole, it's hard to get out.