system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: There are times when a one-way airplane ticket will cost 3 or 4 times as much than a return airplane ticket. What stops people from simply purchasing a return ticket and not returning?
gpt
Nothing.  You can take advantage of this loophole.  

In addition, if you happen to know that a multi-stop flight that stops at your desired city costs less, then you can book it and simply not board the follow on plane.  

Both of these take a little homework, but I've done it before.