I had a work acquaintance who was otherwise very intelligent. But he was also way deep into alternative medicine. His mom had cancer and finally gave up on chemo. So he and his wife got some alternative medicine "doc" to see her and he prescribed, among other things, coffee enemas. My friend was all excited when those blackened, dead cancer cells were just "pouring out of her." Hmmm...
When she died a short time later, all they said was they had started her treatments too late.
When a person, no matter how well educated, decides they believe something, no amount of scientific evidence or other proof will convince them otherwise. Just like the way religious superstitions get ahold of people who should know better.