a glutton for punishment
A person who continues to do things whose consequences they find difficult or unpleasant. I couldn't wait to finish college, but I soon found myself in grad school. I must be a glutton for punishment. Why does George keep getting detention? Is he a glutton for punishment?
a ˌglutton for ˈpunishment, ˈwork, etc.
(informal) a person who seems to like doing unpleasant or difficult things: You’re going to drive all the way to London and back in a day? You’re a glutton for punishment, aren’t you?She’s a glutton for work. She stays late every evening.A glutton is a person who is too fond of food. In this idiom, it refers to a person who seems to be very fond of the thing mentioned.