of course not, that's on valve, just like Days under Custody
No, it isn't. It's on the store that sold them and couldn't afford the cost.
You have basically zero protections when selling keys on ebay. Don't even try to sell there, it's nothing more than a cesspit of lowlife scammers.What if you sell an Nvidia promo code on eBay and the buyer just blatantly lies after paying and says "the code says already redeemed."
There's nothing you can do, right? If you tell him to fuck off, he'll just give you a negative feedback score. You just take the L, refund him, and move on?