Here's why:
Antisemitism
Bigotry
Crime
Corruption
greed
Too many people coming into the country illegally.
Commercialism out the ying-yang.
Selfishness
People behaving like a total bunch of fucking assholes,
Political correctness.
Nearly NO freedom of speech.
Need I go on??????!!!!
ALIENS FROM OTHER PLANETS SHOULD THINK TWICE ABOUT VISITING EARTH!