Extraterrestrial beings visit Earth because
1. They think us interesting and want to be our friends.
2. They want to eat us.
3. Watching us destroy ourselves amuses them.
1. There are more than one type of extraterrestrial beings, from more than one place. Some want to be our friends. Some want to eat us. Some want to eat some of us.
2. There are extraterrestrial beings but they do not visit us and do not care about us.
3. There are no extraterrestrial beings.
Tell your friends.