Legal hassle? How would there be legal hassle? There’s nothing requiring them to allow this to happen. In fact, it’s against the terms of service.

You’re just making up excuses for why they should do nothing, when it’s easily within their power to stop it. They did a lot of work using machine learning to detect hackers in CS. That same thing could trivially detect accounts mass-trading and link them to gambling sites, then block them. If these companies lose enough money, they’d stop popping up.

Most players don’t participate in this, so the vast majority wouldn’t care, and likely would praise them for it.