Team sports. You bought the glove, the cleats, the bat bag. They picked grass in right field and sat until the last two innings while the coach's kid played every one. Sometimes it's the wrong fit for the kid. Sometimes the roster is just too deep for them to get any real reps. Either way you end up paying for a season your kid mostly watched.
Other martial arts. A year contract for a five year old. Belt tests every couple of months at sixty dollars a pop. Three belts later you couldn't name one thing they actually learned. Twenty-five kids, one instructor shouting over them, and your card kept charging two months after the contract ended.
Dance, gymnastics, cheer. The first six weeks are great. They love the outfit and they show you every move in the living room. Then it turns into a fight to get them in the car. A lot of these programs are built around the recital or the competition team, so the kids who were already good get the attention and everybody else learns the routine from the back row. Your kid figures out pretty fast which group they're in. You end up with a two hundred dollar costume worn twice and a kid who's a little more sure they're just not good at things.
Talking to them about it. Just ignore them. Just be confident. Use your words. Dad said toughen up. None of it moved a single inch, and it never will, because you cannot talk confidence into a kid. They don't have a knowledge problem. They already know what they're supposed to do. They've just never once done it and come out the other side.
Screen limits and sticker charts. Timers on the iPad, chore charts on the fridge, a sticker for every good day. It works for about three days. Then the timer turns into a negotiation, the chart falls behind, and you're right back where you started, only more tired. That's not bad parenting. It's that a chart can only manage the behavior, it can't touch the reason for it. A kid with a tank full of energy and nowhere to put it doesn't need a better chart. They need somewhere to spend it that gives something back.
Every one of those failed for one of three reasons. It didn't work on the actual problem. It didn't fit your kid. Or it was built to take your money and never had to prove it changed anything. That's the whole list.