Used games are certainly not as bad as piracy for two reasons:
1.) Used games do exist as part of a secondary market. When someone sells their games to a store for credit, they will occasionally use that credit to fund a new game sale. They may also become a legitimate regular retail supporter of further new copies based on a positive experience they had with a used copy (much more likely than a pirate who got something for free actually deciding to spend money on it's sequel no matter how much they liked the one they got for free).
2.) No new copies are created. In a used game sale you're still only seeing a unique copy bought and sold, so the magnitude of profit damage is kept in relative check. With a pirated copy, however, even if we assume that the original ripped copy was a legitimate purchase, it is still able to spawn infinite copies of it's own. A single copy of a used game may see, for example, 10 owners. A single pirated copy, however, may be stolen by hundreds of thousands.
1.) Used games do exist as part of a secondary market. When someone sells their games to a store for credit, they will occasionally use that credit to fund a new game sale. They may also become a legitimate regular retail supporter of further new copies based on a positive experience they had with a used copy (much more likely than a pirate who got something for free actually deciding to spend money on it's sequel no matter how much they liked the one they got for free).
2.) No new copies are created. In a used game sale you're still only seeing a unique copy bought and sold, so the magnitude of profit damage is kept in relative check. With a pirated copy, however, even if we assume that the original ripped copy was a legitimate purchase, it is still able to spawn infinite copies of it's own. A single copy of a used game may see, for example, 10 owners. A single pirated copy, however, may be stolen by hundreds of thousands.