I think the day to day joyless grind of survival has strained a lot of folks to the breaking point. I agree that it’s always been like this, and that the lethal results are just getting more news coverage.
I also think the myth of the American Dream plays a part. We are constantly told that the only reason we fail in America is because we didn’t work hard enough. We are collectively working our asses off, and it is never enough. Most people are either getting nowhere, or sliding backwards, and the moment we speak about how this system is killing us, we are told we are lazy and our misfortunes are all our fault. The problem is never the capitalist system with corporations becoming our feudal overlords.
After a while, a person explodes over a trifle because their life sucks.