One of my kids was reading the instructions for Monopoly (I think she thought I was trying to cheat), and said “Look Dad, if the bank runs out of money it says we must make more using bits of paper.  Pity we can’t do that in real life.”  “Oh, but, my darling, that’s exactly what happens”.  Well, if we can just make more of it, why is it worth anything?”  “Because everyone says it is”.