I wonder how many total people were paid for their domain sales with fake money without wanting or agreeing to the fake money. This scheme alone could be millions of dollars.
I will probably take a lot of downvotes for this, but
all fiat money is kind of "fake", by this reasoning. Masterbucks was supposed to be "equal" to 1 USD. So, it doesn't change much, in the end.
When DAN or Afternic receives the money for your domain from the buyer, the situation is pretty much the same. Where it changes is that they pay you out immediately just after. With Epik you had to specifically ask for the payout (and you still do if they give you in-store credit.
Can you even withdraw these, or you simply cannot?). Quite some people let the money there, and Epik used it, spent it, or did God-Knows-What with it. The real problem is the latter.
You can argue Masterbucks may have enticed people to leave money at Epik. Especially with their initial claims the domain sale wasn't a taxable event if you let the proceeds in Masterbucks and reused it to buy other names. Claim which might be highly debatable.
But until you get your money from DAN or Afternic, they also owe you that money for a short period of time. With Masterbucks, Epik owed you money. If they had kept it safe for you, all would have been quite well. They didn't.
The "fake" argument. Meh :/
When a bank goes belly up, it's the same situation. Reason why there is a need for guarantees behind, like the FDIC in the US. This is the definition of counterparty risk. Don't like it? You'll love Bitcoin. If you understand it well.