One of the biggest things I've changed my mind about is why gold stopped being money.
Gold was one of the greatest forms of money humanity ever used. The problem was that civilization kept growing while gold remained physical. Banking solved the growth problem, but it created a new set of problems that we're still dealing with today.
Sound money didn't disappear because of a conspiracy. It disappeared because civilization outgrew gold. Understanding that history matters if we ever want to build trustworthy money again.