Because they don't wanna admit how little control over their lives they have so they do stuff like this to imitate control. The material reason is because institutions in America like healthcare and education have failed and so people escape into alternatives no matter how ineffective.

If you wanna be a bit more positive about it, I think this could be labeled benign superstition. The male equivalent of healing crystals. In the age of the internet, what used to be believing in evil spirits or demons has been replaced with this kind of crackpot science for a lot of people.

This is admittedly a rather generous interpretation but this isn't much sillier to me than hanging a dreamcatcher above your kid's bed. It doesn't actually protect them from anything but it shows the dad cares, kinda.

All it takes is to double down when wrong, and it'll spiral from there. It would start by something very small but wrong and they get defensive when challenged on it. They do their own research and ~~confirmation bias~~ present it as proof they were correct. Counter-proof sends them further into the spiral with even more energy. All of this is magnified once it becomes part of their identity.