One need not be &quot;disturbed&quot; to carry out horrific acts of violence. Would you describe a fanatical terrorist (ISIS, Skinhead, whatever) as disturbed? Writing off anyone who decides to murder as &quot;disturbed&quot; is ignoring a whole swathe of folks. The US has easy access to firearms, and we glorify violence. There are many reasons why one will kill, and just saying &quot;Oh, he&#x27;s fucked in the head&quot; is just another way of shifting focus from other problems.