You've missed the point of the article I shared with you. The point was normal people under extraordinary circumstances can be pushed to breaking point and take it out on others. Normal people do not always behave normally.
Not everyone is "wired" to deal with life's challenges the same way. I had a friend who committed suicide after losing his business in 2009. Sad. On the other hand, I've been bankrupt --as in lost it all, not a dime to my name-- and suicidal thoughts never entered my mind. In fact, I hussled and worked hard for very little until I could start a small business.
That article has an agenda, follow the money trail and you might discover what it is.
As for the article's agenda, perhaps it had one, but it appears to be an agenda backed up with facts, for example:
“Fewer than 5 percent of the 120,000 gun-related killings in the United States between 2001 and 2010 were perpetrated by people diagnosed with mental illness,”
When we look at violent crime we see almost all perpetrators do not have a diagnosed illness, and also they do not have a diagnosable illness.
You are falling for the conjunction fallacy. You see "violent", and insist "violent and mentally ill" even though violent is more probable.
You are an intelligent person. You HAVE to know that I do not mean someone with autism or a developmental disorder. That would be sick and repugnant. But that's not what I mean. And you know it.
What I mean is someone with such a mental illness or sickness or reality distortion that they can justify picking up a gun and killing twenty children. A person has to be sick in the head to do something like that. Sick in the heart too. Use whatever terms you care to pull out of the dictionary but we all know what we are talking about.
Someone has to be "crazy" (define it as you wish) to behave in such ways.