The threshold to cash out seems high, but the percentage cut is curious, and I'm not convinced "exploitative" is the right word. It's a high cut, but is there anything else that makes it anywhere as close to make a game and share it with your friends? It seems to be in an entirely different league as any of the app stores or PC game development, so a higher cut there would make sense.

The "it's just for fun!" argument does cut both ways - then why introduce real money into the ecosystem at all? - but has an obvious "because real money is needed to make the product and ecosystem exist" answer. Is taking this much real money necessary? That seems like a much harder question. You could say it's a bit like college sports - playing a game with your friends and there's some institution that's taking all the money, and then, yes, if Roblox is rolling in huge profits and distributing a penance, they deserve some pressure on that.