If I have to violate terms and use VPN, I might as well use Binance.
How common is it that people do that? Doesn't that weigh on your conscience during your trading activity? It would for me. Plus, if they catch you, you can probably say good bye to your money.
People have been trading this way on Bitmex for years. They prohibited US residents since at least 2014, possibly since launch, although they didn't start IP-restricting until a couple years later.
As a matter of policy, they just close your positions and ask you to withdraw your money. Even if they had a legal right to steal your money for violating their terms of service, it would be bad business.
It's no different than going into a casino and figuring out how to game their system and beat their house. You can bet your bottom dollar that the casino has people watching out for customers that are sneaking around and bending their rules, even if just a little bit.
It's a quid pro quo, a favor for a favor. Bitmex ignores all the US traders violating their terms while benefiting from all the liquidity they bring. It's how they became the biggest derivatives exchange in the world. Binance is in a similar position now.