In my understanding of fun theory, you have worthy adversaries, but low consequences in case of failure. Like a video game, where if you lose, you lose a few hours of gaming at worse. Not that if you lose, you end up in Azkaban feeding the Dementors.

At least for myself, I like hard games, not easy ones, but I like it when defeat isn't too severe; I do sometimes play games in "iron will" mode (no saving, if you lose, restart all from the beginning), but not often, it's really the upper limit to what I accept when losing.