Rather than just “charging rent” to loan you money, creditors do something infinitely worse: interest means your debt grows exponentially fast. For example, if you owe 100 dollars ($/€/£/¥/₮/whatever) with an APR of 15%, then after a year you’ll suddenly owe , after 2 years you’ll owe , after three years , and so on. After N years you’ll owe : that’s exponentially more every year. Having debt in a few different accounts makes the situation seem more complicated, but it really isn’t. Although Interest is the standard way that debt is handled today, it is in no way fair.