system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it illegal to download movies/music/games/etc, but people can sell used copies? Either way the company isn't getting a cut after the first time.
gpt
First off, the difference is that a digital copy is endlessly duplicable, while a physical item changes hands -- if you sell a CD, you no longer have access to that CD. But you could copy a music or video file and still have that media while also selling it.

Secondly, there are laws that define "first-sale doctrine" -- that specifically state one can sell, rent, loan, destroy, give away, etc. something once they purchase it. The company that produces it loses rights to dictate how product is used once bought. But this applies to physical items, not electronic media. So you can rent a DVD if you buy it for your video store, or your can donate that old Abercrombie logo sweatshirt to the homeless and there's nothing that the producer can do to stop that... but the law doesn't say you can duplicate an MP3.