“Beliefs” come in all shapes and sizes, and most of them are ridiculous. Here is a great example of how ridiculous they can get, and how widely they can spread despite being ridiculous:
The article describes it this way:
I just arrived in South Korea, and my colleague says that I can die if I sleep in a closed room with a fan on. He insists that “fan death” is an actual danger. What the hell?
Hodges also shared the following passage from the government-issued Cultural Guide for Migrant Workers in Korea: “In some cases, a fan turned on too long can cause death from oxygen deficiency, hypothermia, or fire from overheating.” “Some Koreans,” he adds, “give outlandish explanations about how the whirling blades of a fan can sever oxygen molecules.”
This belief is unique to Korea, but it runs very deep in Korea even though it is ridiculous. The fact that the rest of the world knows that “fan death” is imaginary is irrelevant.
How does a ridiculous belief like this get started? There is no way to know. Like the fear of the number 13, it is inexplicable.
How does it gain credence? Perhaps, at some point when this belief was first forming, two or three people died in their sleep, AND THEY HAD THEIR FANS ON. The fact that they were 97 years old when they died in their sleep was irrelevant. The belief became “real” to people.
Parents then convey this belief to their children, who hear about it from infancy on.
Occasionally the belief is reinforced when a person dies in their sleep WITH A FAN ON, and the story makes the news. All the billions of people around the world who sleep with their fans on without incident are ignored.
And then, each individual person reinforces the belief. If you live in Korea, and if you have heard this myth all your life, and if everyone around you believes it, and if you hear stories on the news, and if you then find yourself in your room about to go to bed, what do you do? You turn your fan off. Why risk death? It is the same as a person in America refusing to stay in a hotel room on the 13th floor. Why risk it, given that you have a choice and there is no cost to avoiding 13? And then something like Apollo 13 comes along and reinforces the myth. It is very hard to eradicate a myth like this once it takes firm root.
Every Religion works in exactly the same way. The beliefs are ridiculous, but for many people they are set in stone.