i haven't done it, but my best friend did. he was in pharmaceutical sales for johnson and johnson, and absolutely hated it. he was always under the gun for sales, and they dangled his job over his head constantly. he knew they were cutting staff, so he actually put himself in position to be let go. at first i thought this was nuts, but he had a plan. he ended up to going back to RIT for packaging engineering. since he had been laid off, he was able to get money, (i really don't know if it was a grant or what) to cover a very large portion of his tuition. i think it was a program where the unemployed could learn a new vocation. years later he now lives in buffalo, works for rich foods, and makes a very good living.
that being said, he did this in his early to mid 30s. he didn't have kids yet, and his wife had a good job in sales. i'm sure this scenario helped him make the decision.