Question

Friday evening, Shabbat Zakhor, 5781.
Something very puzzling keeps appearing before my eyes again and again.
Communities and groups of intelligent, moral, Torah-observant, thoughtful, high-caliber people, with common sense,
and many other virtues as well.
But then,
suddenly, when certain topics come up, suddenly they become foolish, ignorant, and devoid of any basic capacity for rational thought.
 
How does this happen? [And how can I protect myself and my household from ending up in such a disgraceful state?]
For example: high-level people in some community belittle death and illness because of the coronavirus—and we are talking about wise people who volunteer to help and save lives…
Or upright people who would never cut corners in order to make money—you can truly see and delight that these are people of God and from His land they emerged. But when it comes to supporting bribery, fraud, and breach of trust, they do not have even the slightest bad feeling about it.
Or people who understand very well what government is and what public order is, and when it does not suit them that someone fleeing the police was killed while escaping, they fill up with claims, conspiracy theories, and nonsense.
And there are many more examples.
[And sometimes—usually, in fact—the men who are supposed to be the spiritual shepherds of those groups do not light the way, and sometimes are even the standard-bearers of the blindness…]
Of course, many times one is simply dealing with fools.
But to my surprise, and from close familiarity, sometimes these are serious, high-level, upright people.
How does this happen?
At what point is a group of people willing to give up reason and conduct itself foolishly [and even educate their children that way]?
How do you avoid being corrupted by them?
 
I would be very glad for an answer.
It troubles me very, very much.