Are there really "many" such beliefs at any given time?

If anything, there are a "few" such beliefs, and it takes a great deal of knowledge and insight (of how the world actually works in the context of "conventional" knowledge) to find which ones.

Otherwise you're unemployable, living in a cabin in the woods, and drinking your pee because you think that's going to save you from the Flat Earth Alien Crystals in the Deep State.