Paper money has been around for a long time, its not a recent phenomenon. And people can just print out more. But see Gods kingdom isnt run with money. Money may make the world go round, but in Gods kingdom, everything is given freely without price.
People actually need to learn to live without money...there are many people in the world who have done this and they are fine. But other countries then want to trade and introduce money systems to cultures that dont have them and these people have to learn to adapt to this way of living ...many dont know know how money works.
Jesus lived without money, he wouldnt take any with him When he was ministering, he got tribute money from the mouth a fish, he fed 5000 with loaves and fishes that appeared without buying anything, and turned water into wine.
Kinda like the queen of england doesnt carry any money in her purse either, but difference is, her queendom is vast, shes got royal retainers and servants and palaces etc. Jesus had no palace, a bunch of fisherman as followers, and he came from the small town of Nazareth in Galilee. He was born in a stable not with a silver spoon in his mouth.
I think more people can relate to Jesus than they can to the queen of england.