I am pretty new to DNMs and just today I had a look at GermanPlaza.. looking at all the CCs they offer I've asked myself a couple of questions.. I've done some reading on this topic, but did not find everything I wanted..
How can the vendor know the minimum value on the card ? If they are there to make money, doesn't it make more sense to actually use the cards themselves instead of selling them for $10-20 ? Is it risky to use the cards in some way ?
It's incredibly risky and difficult. These vendors have 100s of cards and each card takes a lot of care to extract the most value from them. I don't actually know the numbers, but if you can sell 100 cards a day for $10/piece, or use 10 cards for $100 of profit, your best bet is to sell them, way less risk to you.
I don't know for certain, but personally I think the cards are just the DNM version of get rich quick schemes. For every pro that can cash out their cards regularly, there are ten people who buy a card or two, fuck it up and stop trying.