Just pull out a dollar bill, and ask someone, "why does this have value?" Or, "why is this money?"

Sometimes you get dear in headlights, sometimes you get "Because the government SAID so." (Rule by FIAT)

I then ask, "Don't people have to agree that it has value? Because in a currency crisis, the government is always going to say that money has a certain value. Does that stop people from dumping them as quickly as they obtain them?"

At this point, most people usually say, yes that's right people have to AGREE that it has value for it to have value. So, it's a psychological transition that can happen pretty quickly. And one big confidence game. You can't have confidence without a CON.