1. You become careful who you associate with
You find out the truth behind "you are who you associate with" when you travel overseas. Always remember you are the average of the people you interact with on a daily basis. If someone is bad for you, then ignore them and cut them off. You are who you talk to and build relationships with.
2. You realize there are a lot of bad people on Earth
The world is full of evil, wicked people. They are literally everywhere. You have to live next to them but you don't have to be like them. Carve your own personality and be yourself.
3. America is becoming a hostile place
From shootings to crime, America has a lot of social issues. Many parts of the world are peaceful and kind. See for yourself.
4. You learn from other people's mistakes
Staying in your comfort zone doesn't allow you to learn from other people's mistakes. Being around a different culture makes your poor habits obvious. You need to stop bad habits and pick up good ones.
5. You become a stronger person
International travel has risks. Many people do not make it back home in one piece. Living overseas tests your strength to survive in a foreign environment. You become harder to destroy.