In a world of billions of individuals you can always find some that believes in whatever it is you're looking for people to believe. OP's point as I read it is

In a world of billions of individuals you can always find some that believes in whatever it is you're looking for people to believe. OP's point as I read it is that once those beliefs hit a critical mass amongst the general population they tend to come true via self fulfilling prophecy. Correlation/causation aside - the point is not "if my uncle thinks a recession is coming, there is", it's "if 100mm American adults think a recession is coming, there is"