Apparently you can reverse a transaction under buyer protection service and then it's a seller who needs to prove they actually sold something. Basically you can go to garage sale, buy all the stuff, get back home, reverse all transactions and say it never happened. Then all the sellers will need to prove you were actually there and received the goods. I heard about it, but I never knew you could reverse it in 10 min without even providing any info. The guy who scammed me left the reason / comment section blank and still got his money back in 10 min.