I disagree that the games are mostly crap... I have 4 step kids who game, and 3 do on roblox a lot. Some of the games may be objectively poor, but they enjoy playing in them anyway, and some of them are spectacular.
I spent quite a few hours playing with them during the original UK lockdown,which was doubly good as I don't live with them so didn't see them for 3 months. In that time we "did" many things,including "going" to a theme park, and spent many hours exploring and seeing how bad I am at it. Without roblox we wouldn't have had that experience.
In terms of scams, I'd rather they learnt using their pocket money than their wages when they are older.
Yeah, like I said, there are some decent games, and the stuff that bubbles up to the top of the list are fine I guess, but if you ever try actually searching for a game you will find a cesspool of crap that doesn't work or barely works or is just stupid and all of these games have exactly the same name because there's no QC. 99.9% of the "games" in Roblox are unplayable.
"Theme Park Tycoon" is a Rollercoaster Tycoon clone that's really nice. It's pretty much single-player, but you can check out other players' theme parks which is very cool.
"Islands" is mostly a Minecraft ripoff but you're building air castles (you can fall off an "island" and die). This lets the kids do all kinds of invented in-game games, such as building an obstacle course for one another, playing hide and seek etc.
"Fishing Simulator" starts out as a pretty dull pirate-themed fishing game but turns out to have a lot of depth, adventure game style. It also has amazing content for Roblox standards.
"Build A Boat For Treasure" is a lot less fancy than the above, but it has a very cool concept. You design & build your own boat, then go sit in it, and take it through a river full of obstacles. The way you build it determines how it deals with the obstacles because when you sail away you can hardly navigate it anymore. So you need to design for robustness etc, which turns out to be pretty hard.
A lot of the games are shit, but also a lot of the games look shit but have super original ideas. Eg there's a game that you're in a building and then some disaster happens (tsunami, volcano eruption, whatever) which slowly destroys the building and whoever survives the longest in the collapsing building wins. I'm really not sure if that's a ripoff of anything, it strikes me as genuinely original. It's not very deep, but it's good fun.
"Roblox Ninja Warrior" - this was fun mostly because the kids could do the courses as they are better at moving than I am. However, they'd sometimes fall off, which is funnier.
"Famous Fashion" was funny - a theme is set and you have to dress up your character to suit, and then everyone votes. I thought I'd be bored in 5 minutes, played it for about 90.
"Universal Studios" was the theme park. Amazingly done.
"Pinewood Space Shuttle" was good fun - particularly if you fall off the shuttle while it's in orbit.
"Starcourt Mall" (Stranger Things) was nice to go there, as we've watched the series together.
"Ragdoll Engine" - as the name implies, just mucking about with the physics of your character.
"Epic Minigames" and "Lab Experiment" have small games in them and they were both pretty fun, plus you're playing against other people. I actually won a round, which the kids never expected, so I became a legend. For 38 seconds.
In terms of scams, I'd rather they learnt using their pocket money than their wages when they are older.