Have we always been 'Mad'?

I don't even know where to begin.  Have we forever lived in a world where people suddenly go crazy and do horrendous things to other people?  Has it always been this way?  If therapist knew why, these killings would have stopped long ago.  Figuring out the killers after they act doesn't seem to help prevent future (at the time) senseless killings.  It's not just one group of people, or gender.  Spouses  kill each other or one of them kills all the children.  Workers go into office buildings and kill their ex bosses and co workers.  Adults kill rooms full of innocent children.  These people even go into malls and kill as many people as they can and then commit suicide.  Their 15 minutes of fame?  I doubt it.  What then?  Do they want  to hurt (among others) surviving family members?  Is this their way of revenge against someone or something that has hurt them deeply?  We can't blame guns or knives.  They aren't the 'trigger'.  Perhaps that's the word 'trigger'.  If we can figure out the 'trigger(s)' then perhaps, we can come up with answers.  Let us hope so and soon..................................marge