I've tried to say this in other ways, but from where I'm sitting it's not JUST "idiocy". There's a healthy dose of FEAR in all this and as we all know, people do some wacky shit in the face of fear. Add to that the fact that we seem to increasingly be a society that is commited to the inductive fallacy, that is, we have a conclusion - often rooted in emotion, not fact - and we fit those pieces of information we have to that conclusion where we need to in order to justify that emotion. "Feelings are facts" is not just a meme or bumper sticker.
I'm going through this with some of my relatives too; it's not about "politics", at least not like we talk about them here. For me, it's flat out fear, and the politics are just the pieces of information that are grabbed onto to sustain the fear. My parents are 81 and 83. Dad has severe acute early onset arthritis; his immune system has been shot for decades. Minor colds are a trauma for him. Mom has Alzheimer's, and is at that tipping point where she's still "mom", but not the mom I remember. These two are a psychologist's wet dream; she's supported him his entire life, did all those physical things he could not do for him, from dressing him to cleaning him to sometimes literally carrying him. He, in turn, did all those mental things that she wasn't great at; bills, banks, insurances, taking care of the home(s), etc. They spend EVERY MINUTE of every day together. She was in the hospital a month or so ago, and it was the first nights they didn't sleep in the same bed since AT LEAST 1990. Now that she has Alzheimer's, my dad feels this deep obligation to return the favor so to speak (I've had to pledge to my dad multiple times that I will take care of mom if he goes first; it's a given, but he wants to hear it).
My dad is the perfect candidate for the shot. 90, 95% of the time, he's all in and wants to get it. He's - mostly - a man of science, but his information sources are limited, and so I don't always know where he's getting his information. I will, on occasion, get a call like this: "Hey Stads [he does not call me Stads], someone was telling me [something fucking ludicrous]". That someone could be a neighbor, it could be Tucker Carlson, it could be something he overheard at the CVS, it could be something a doctor/nurse told him. Who knows? And I do what I can to set him straight, but I'm only as good as the questions I get. I've been trying to get him one (Florida can blow me, BTW) and I will, but in the meantime, I have to basically "manage" him and make sure the fears and concerns don't overwhelm. He's literally more afraid of dying than all other fears in his life combined. That feeds this stuff. While my dad is not what he used to be, by a long shot (he was, literally the smartest person I've ever met) he's no idiot. He IS, though, a scared, tired old man who is overwhelmed with life and information, and a soupcon of desperation.