Easy to say, not so much to convince kids. Keep in mind they want to play Roblox mainly for 2 reasons:
- internet videos (much like Minecraft, Roblox is its own video category on YT, tktk, insta, twitch)
- their friends play
That's the biggest fight, no matter how good some other game you make them play actually is, they will feel attracted to Roblox because of social pressure. If you want to see a similar effect among adults, look at football (either normal or murican) and EA's digital offerings