ELI5: Explain Like I'm 5

Free-rider problem

The free-rider problem is when people do not have to pay for something, but still get the benefits other people paid for. Imagine a group of friends going to a movie theater. Everyone pitches in money to buy the tickets, but one friend sneaks in without paying anything. Even though they didn’t pay, that friend still gets to go to the movie with everyone else. That's a free-rider problem.