They're bigger than Activision iirc. People Make Games did some quality investigative journalism on Roblox to report on how their wealth is built on the back of child labour - most of their games are built by children who are paid in Robux (company scrip) with unreasonably high cashout terms and immediate massive devaluation, with the intent to keep the scrip in the system. They also have speculative investment / gambling fuelled, again, by children.

One line that sticks out is "What Roblox is doing would be illegal, if it weren't being done online"