People who don't "do" irony ...
They're the people who scream Don't get vaccinated against Covid - and then die of Covid.
They're the people who yell Don't tell ME what to do with my own body - and then attack those who are getting vaccinated because they are choosing to do what they want to do with their own bodies.
They're the people who claim dominion over their own bodies when it comes to refusing to protect themselves against a deadly pandemic - but believe the government has a right to tell women that their bodies are subject to government interjection.
They're the people who claim to be Jesus-loving Christians while voting against any efforts to feed the hungry, shelter the homeless, or care for the sick and dying.
They're the people who call themselves "patriots" while storming the Capitol in an attempt to overthrow democracy, and kill those trying to protect it.
They're the people who epitomize the concept of irony - but are just too stupid to appreciate it.
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as far as IQ, half the rest of the people in the whole country are dumber. However what you say adds a new dimension, cruelty and lack of compassion for other human beings. I assume that correlates with IQ 
And that goes beyond IQ. Very intelligent, well educated people can be extremely cruel and insensitive. They are often the most dangerous, using their superior brains to look down on other less worthy people, while exerting power over them. Many of them tend to go into politics.
Some of the kindest, most compassionate people I have known did not have high IQs, but they had enormous hearts and a moral center.
though I have encountered quite a few anti vaccine people who appear to be relatively intelligent, but also brainwashed. It is such a weird phenomenon, as you can't always predict who will take the crazy path. My ex husband is one of the smartest men I've known and he's bought into the most bizarre conspiracy crap. We were all shocked. Some people just seem to be more vulnerable, even if they are smart.
I don't think there are any simplistic answers, though certainly lower intelligence people would usually be more susceptible. That drawing board has gone through a whole lot of changes the past four or five years! 
to recognize that the damage to their brains is more significant than they realize. A brain that is broken in the way that theirs is cannot be reasoned with.
