Another big downside: when you pay something with cash, it hurts. It physically hurts. You give your hard earned cash and get back the goods. Cash is gone. But when you pay with a credit card, you give your credit card to cashier, she gives you goods and your card back. It doesn't hurt. Your brain registers this as not spending because you got your card back. As a result, people spend way more when they use cards in comparison with cash.