> "folk economics" implies it is by untrained people.

The problem is mostly its appropriation by untrained people though.

> Milton Friedman's famous quote of "inflation is always and everywhere a monetary phenomenon" shows that he deeply believed the relationship between inflation and money supply

Creationists theoreticians believe in creationism too. The problem arise when their theory reach the mainstream… (Influential people inside the Swedish Central bank making a fake Nobel prize to promote these ideas didn't help of course…)