You're forgetting a very important topic in finance: positive cash flow. While saving that $100/mo I have an additional $100 in my cash flow that can be diverted in the event of an emergency. Instead I have a $107.20 credit card bill. So how will I pay for that flat tire? You guessed it, I'll put it on the card. If you're the type of person who has a sufficiently large emergency fund and savings, you're probably also the type of person who doesn't need to spread the cost of a TV out over a year.