Let's say I've bought these bogus cards. This is the starting point, with dirty money. Anything bought here is obvious and traceable. I take that money, and I buy Visa gift cards, which basically function as cash. I take those Visas and buy Amex gift cards, losing 6% (ballparking here, it's actually 5.95% for $100) of my take to fees and then another 10% to fees/shipping for Amex. I funnel those through fake app purchases on the app store and lose a further 20% of my original take.

I now have about 55-65% of my original take in relatively clean money that I convert to bitcoin and back. If you're talking thousands of dollars here, this can easily be worth it. Doubly so if you live in a country where the expectations of police are that they're not going to have the resources to pursue this kind of crime for whatever reason. Get enough people doing this and enough accounts to make the flow through multiple channels, and you've got yourself the makings of a multi-million dollar money laundering service you can sell out to identity thieves (or use for your own thieves).