#20 Humans are naturally judgmental. It may seem like being a jerk, but it's fundamentally a way for individuals to learn the social norms of a culture and be able to fit in. When you see someone behaving differently from everyone else, it subconsciously teaches you what not to do so you don't stick out. When in Rome...

Today, though, it's fueled by some sort of social norm to look as hard as you can at everyone so you can find something to be offended by and complain as loudly as possible about it for attention.