> in the worst case you're buying bogus keys or stolen accounts

Maybe this is just a hole in my knowledge but I don't see how this could be the case.

Regarding stolen accounts: Once I activate a Steam key, I can't deactivate my copy to get my key back (I don't think anyways). How would a stolen account generate steam keys?

Regarding bogus keys: If the keys primarily didn't work I suspect that we would see deplatforming of the site by payment processors. They generally don't like when all their customers issue chargebacks.

I think there is some risk that keys sold in a grey market are purchased by stolen credit cards but I can't imagine that this is too prevalent. I would think that the credit card owner would dispute the charge and Steam would deactivate the key.

> I would think that the credit card owner would dispute the charge and Steam would deactivate the key

There's a real issue for both Valve and the game dev if this happens. The public isn't going to take this key doesn't work or worse my game stopped working after I bought it and blame nebulous credit card fraud, they're going to blame Valve and/or the dev