Maybe just a little bit of a way to remove the dopamine high, or make it slightly worse, would be to have the kid physically hand you the money before they open the case so they feel the pain of spending the cash.
Well, you can do it the good ol' way with ceramic piggy banks that do not open but need to be crashed with a hammer.
Anecdata, I had one in the shape of a dinosaur, must have ben 5 or 6 and I still remember (some 50 years later) the day I decided that I needed a new toy the doubts about actually breaking it (with the assistance of my dad) and perfectly remmber the dinosaur, whilst I cannot remember at all which toy I was willing to get, probably a toy gun, but I am not sure.
maybe... though, I think even at that age we are all the same with respect to losing things that you had. i think though that if you are letting your kids do lootboxes before they have earned the money to open them it's probably too soon anyway.
