Be careful what you wish for. I thought the same thing when our kids were in Tae Kwon Do. They stopped at ages 10 & 13.
Financially, it was killing us, especially x2 kids, but it was good for them. One kid, now 20, is very into gaming so it got him off his rear and kept him fit. After he got his black belt he didn't want to do it anymore and has gotten a tad rounder since. We're not very athletic people or into even watching sports so this was so good for him.
Without having this to keep ds16 (then 12,) occupied a few nights per week, he entered HS and started hanging out with the wrong crowd. It's been a long road since then and he admits he was foolish back then, but still I'd love to go back to taking them to karate and even paying through the nose for it.
Having SOMETHING to do keeps them out of trouble. Kids are often insecure at that age and will do ridiculous things to fit in & look cool.