To spend that extra energy and time you don't have, to make something that's worth making, to make it awesome, wears you out. It's a beast of a show. And the more popular it gets, the more the ancillary things – like the merchandise and games and everything – keep getting bigger.
I quit because it was driving me nuts. For me, having quality of life outweighed the need to control this project and make it great all the time.