Many humans see themselves as independent absolute monarchs of their world. The reality of "we're all part of an interconnected system" is so incredibly offensive on some super-sensitive egotistical and narcissistic level that they will literally become violent to defend it.

If there's one thing we should be teaching in schools, this is it. You can leave school and have no clue that everything is connected to everything else, and that if you're not focused on that reality your actions can have completely unexpected and counterintuitive (to you...) consequences.