Why are there fake people?

This should actually be in the health, psychological section, but I'll answer it on here anyways.

1. They're insecure. Most people hate on others because they're insecure themselves, therefore reflecting themselves back onto others.

2. They're trying to be nice, but don't really like you. I've been called fake before, which to an extent could be considered true. But I believe that I should be kind to others no matter my opinion on them, which comes off badly sometimes because they assume I like them just because I'm being courteous.

3. They're trying too hard. People will often act unlike themselves, or like another because they've convinced themselves that it would make them and others like them more.

A fake person is someone who is not genuine and will do whatever it takes to make themself look good