Shalom,
When I was young there was a system set up by society to protect the sane population from the insane population. This was known as the Asylum system, where people deemed to be a danger to themselves and society would be involuntarily kept under observation by 'mental health' professionals. This system did a lot to protect the greater majority of America from the minority of dangerous mental cases, either homicidal, suicidal, and/or delusional... Of course there are stories of people who were kept in the asylum who may have been sane by some standards, and there were cases of abuse of some patients, but overall the peace was kept in American society.
Over the last 10 years I have noticed an uptick in the number of stories where a lone mental case is permitted to buy weapons (either guns, knives, or explosives) and they go crazy on innocent people. Usually I find the cause to be involving the 'entitlement attitude' causing a person to flip when the reality of the situation does not jibe with the fantasy they have. And of course most of these cases involve a poor shlemiel who believes the world is unfair to him, and he has a right to inflict his retribution against society. They want people to notice them, and they act out to get attention. The media always looks for the requisite 'manifesto' where he or she explains why they are justified in their crimes.
See what the PJTV Trifecta gang says about it...