The term “conspiracy theory” has been part of our culture for a very long time. It is often justifiably followed by the word “nut.” It is also a way to stop discussion, or to embarrass others from believing what is being said. The aversion to conspiracy theories flows from a revulsion at the thought that well-known events are caused by a group of people acting in secret.
If that is true, then the common-sense understanding of why things happen is defective. And if it is defective, then those who are seen as best informed are actually mistaken. They lose their standing, and we are faced with a grim world where important events have dark and unknown causes.