system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What will happen to the world-wide economy if America were isolated from the rest of the world?
gpt
Imagine your school allows the sale of candy between students. This rich kid absolutely LOVES candy and the parents are all too happy to give the kid money because they have a ton of it. He literally is buying up 15-20% of the candy by himself. With all this money, more and more students get into selling candy because they see their buddies making all this money! The candy market is booming! 

All of a sudden, the kid moves into 6th grade and in to a new building. Now there is so much candy that ISN'T being bought. The kids selling candy had bought so much because they were able to sell so fast. Kids were using their candy profits to go buy video games, lunch food, playing cards etc. 

Now in order to get rid of the loads of candy they bought, they have to sell it for cheaper... and cheaper... Now less and less kids decide to sell candy because there is so much uncertainty. They're not sure if they could sell a piece of candy for .10 let alone a dollar. And since there isn't money being made in candy sales - these kids aren't buying playing cards off each other, they're not going to the movies... It may takes years for the candy market to recover and all the other things the candy sellers used to buy with their extra money will also suffer.