When I was a young adult it dawned on me there is such a thing as collective insanity. I was reading about Japan near the end of World War II. The Japanese collectively refused to believe they could lose the war, and continued behaviour that was very destructive for themselves and others (they are not unique in this respect, they were just the example I happened to read about). It took the atomic bombs to shock them out of their state of psychological denial.
One view of insanity is the continuation of behaviour that is detrimental to one’s self, despite ample evidence of harm being done. How sane are we now, those of us who live in the rich countries?