All the victims should form a group and launch a class suit, 1XBIT have huge money to advertise and pay people they can continue to do what they are doing.
Unfortunately it seems not realistic to me. The only possible way will be someone to start a massive campaign against them. It will obviously need a fund. Someone who is responsible and trusted can monitor the campaign / project. But I do not think anyone will be much interest to do so, even a lot of gamblers are fine to lose their hard earned money.