Roblox and spending real money - help

Found out my 10 year old has spent like $47 on Robux in the past month. He says his friends have better stuff and he feels left out. I set up parental controls but he's found ways around them. This game is designed to make kids want to spend money and it's pretty predatory honestly. Any parents figured out how to handle this without being the total bad guy who ruins his gaming?