Does anyone know how MU collected money? With all of the restrictive ToS used by payment processors these days, I am very interested to know how they were able

Does anyone know how MU collected money? With all of the restrictive ToS used by payment processors these days, I am very interested to know how they were able to maintain an income stream, for so many years, while their payment processor must have been aware of the potential illegality happening at MU. I'm not making a statement for or against MU, just wanting to know how they were able to keep going when an entity such as WikiLeaks, or a small guy on PayPal who has one chargeback, are so easily financially cut off.