No, the developers don't keep the money.

21 Feb 2012

From The Curious Case of the (Cr)apps that Make Money:

After a day or so, Apple notices that these apps aren’t actually providing they promise and kick the apps out, but not before users spend tens of thousands of dollars on the apps – money that the developers get to keep, as users rarely ask for a refund.

I think it's a little naive to think these developers get to keep their ill gotten wages. Just because users rarely ask for a refund (true or not), does not mean Apple is not penalizing the developers or failing to pay out on their App Store accounts for these fraudulent apps.

Now, it's possible I'm wrong - that Apple is still paying out these account, but I don't see any evidence of that in this article, just assumptions.  It seems completely obvious to me that Apple would "stop payment" on these fraudulent accounts as soon as it realized the issue.