It's not about refunding the customers though. It's the payment gateway that will drop your as a customer. Neither them nor Visa/MasterCard want anyone running scams via them.
If I were running a scam, I'm pretty sure at the moment I would have a positive cash flow: a lot of people are transferring their USD/EUR into my bank account because they want to get on the Bitcoin train. If a few people are cashing out, I'm pretty sure I would be able to manage to give them their payouts. Exchanges also have a withdrawal limit of a few K's per day, in my ponzi scheme if someone wanted to withdraw 100K it would take maybe 10 days, and one hopes there are enough new suckers that each day I'm able to pay out, out of my official bank account, my slush fund. The rest of the money can be transferred out where no one can touch them...
And when the whole thing blows up, I disappear. My payment gateway will drop me, but what do I care?
