Extremism! Yes, I hear a lot of people say it's religion, politics, etc. But truth is most of these things exist in the first place to make life better for us all. Extremism involves taking things too far, religious extremism for example has led to too many bloodshed, political extremism has led to riots and too many unhealthy activities within the political atmosphere. I'll just keep things short: Extremism is the culprit. We can totally avoid it by being accommodating with other people's views, beliefs and interests.