They created the system that allows it. StarCraft had user generated content, but no real gambling because the games ended within an hour or so, and no state was kept.

If they want to create a platform for children gambling and facilitate the payments, yes let's figure out how to send them to prison. They're not stupid. They know all of the reasons why they have a $60B market cap. That's 2/3 of Nintendo for making a "free" game.