

I assume the main issue is that downloading from somewhere like steam and activating with a code, largely ensures there’s no malware included in what you just downloaded.
If you’re pirating something and certainly if you don’t know what you’re doing, you can’t be entirely sure the game you just downloaded isn’t a security risk.

I always assumed it was largely money laundering.
Claim to have bought a key for 1$ sell it for 10$. Declare you made a 9$ profit. In reality there was never a key for 1$. You bought a 10$ key with dirty money and are selling it at cost.
Fundamentally no different to the mafia run pizza place.