system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are people turned down from jobs because they are "over qualified"?

Or what makes a person overqualified? Where is that line drawn of perfectly qualified and over qualified. I'm sure it has something to do with being able to stay "interested" in the work or something along those lines. Anyways, just curious.
gpt
Imagine you have two applicants for a job flipping burgers at your restaurant.

One of them is a high school dropout. He's not going to be able to get a job that's much better than burger flipping, so he's probably not going to quit. Heck, you can probably force him to work unpaid overtime, and he won't do anything but whine to his friends after.

One of them is a Ph.D. There are lots of better jobs a Ph.D can get, and if/when she gets one, she's going to be out the door in a heartbeat. She's also much less likely to just sit there and let the manager abuse her; she may even try to sue you if you make her work unpaid overtime.

So it's actually *worse* for you to hire the Ph.D than to hire some random high school dropout. Thus, overqualified.