Collective illusion is a phenomenon not always well understood, but well known in psychology.
Mass hysteria is capable, within an entire population, of provoking strange beliefs, but also very real symptoms.
The human brain is able to find connections even where there are none, because it is hungry for rational things.
A belief is extinguished not because people become reasonable, but because the illusion has received magical control and symbolic recognition.
If there is a need for an example, we can cite this anecdote:
On the west coast of the United States, in the spring of 1954, a disturbing phenomenon occurs. Many car owners report dips, dents and small holes that dot their windshields. Even a naval air base has cars riddled with these mysterious holes.
On April 14, a Seattle daily writes about these strange phenomena in its front page, and from there, everything rushes. The same night, the Seattle police received 242 calls from people who noticed the phenomenon. More than 3,000 damaged cars are counted. The mayor of the city appeals to President Eisenhower. The explanations are: meteorite dust, radioactive fallout linked to an H-bomb test, a new navy radio transmitter capable of converting electronic oscillations into physical oscillations, the earth's magnetic field being displaced, cosmic rays or spawning insects in windshield glass.
The explanation is found by physicists and chemists at the University of Washington commissioned to investigate. They write in their report that these phenomena increase in proportion with the mileage and the age of the car.
The local dailies for several days devoted their front pages not to mysterious phenomena, but simply related the fact that residents for the first time looked at their windshields instead of looking right through it.
All of these people were victims of a collective delusion.