Browsing the gift cards I see quite a few that are asking for more than what the card balance is worth, seems way too many to be a mistake so what am I missing here??? 
I’ve been curious too and I’m already aware of the common guess of converting illegitimate money, which could be it I guess. I wonder if that money over the original balance is profit for someone in whatever the deal is. Or maybe listing those but making sure they won’t sell is a benefit somehow that I don’t understand?