Money is only as valuable as people’s belief in it. After all, you can’t eat it, wear it, or take shelter under it. Money is, ultimately, a convenience we all agree upon as a society. After a deep crisis that affects all or most of society, that agreement can break down and often does. In such instances, paper money quite often loses value rapidly and becomes worthless rather quickly. When this occurs, people become immediately much more practical and less philosophical. Instead of giving you a perfectly useful pair of shoes in exchange for a pretty useless piece of paper, they’ll start asking for a couple of fresh killed rabbits or a basket of apples. Tangible items with real life uses and value become the medium of exchange, not paper money.