I am looking for a word or phrase for wanting someone to fail, but only to teach them a lesson.
It's not easy to explain. For example, when you tell a child, "Don't run down the hill or you will fall," but they continue anyway. To prevent them from doing this in the future on a bigger hill with a much more harsh outcome, you want them to fall so the lesson can be learned.
You want them to learn something the hard way.
It means to learn something by an unpleasant experience.
once bitten, twice shy
Once hurt, one is doubly cautious in the future. This seemingly old observation, presumably alluding to an animal biting someone, was first recorded in 1894.
The American Heritage® Idioms Dictionary
Variations: once burned, twice shy (or wary or warned.)
The burned hand teaches best. After that, advice about fire goes to the heart (J.R.R. Tolkien)
The Two Towers: Being the Second Part of The Lord of the Rings
I would say 'didactic failure': didactic comes from the Latin verb doceo, meaning 'I teach'. As for wanting this to happen, I don't believe there is such a word in the English language, although the German loanword schadenfreude means taking pleasure from someone else's failure, so perhaps you could work out some combination between the two.
What about "CORRECTIONAL SUFFERANCE"? I wish him to undergo this correctional sufferance so that he may not falter again. It is no reprisal but revisionary.
Perhaps "(I'm going to) Let them(him/her) make their(his/her) own mistakes"?
Generally I would use this phrase for a situation that I don't think is terribly damaging, but serves a good purpose as I don't feel like the lesson will be learned any other way.
