Kids are not going to see a dime of that money. It will get spent on a lot of political churn, propaganda, pet projects, and maybe some programs that will pay for a couple of hours of counseling for the kids.
It's government action, not a civil lawsuit. Of course the kids aren't going to see a dime of that money. If they want cash, they (individually or as a class) have to sue Meta themselves.
Who cares? If it’s taken away from Meta and can no longer be used to build more technologies for Meta, that’s a massive upside to kids all by itself. Doubly-so if the fine incentivizes Meta to stop doing this shit. You could put the money in a big pile and light it on fire and it would still be a net win for society.