That would be true if all credit card customers pay their monthly bills in full, every month. However, that is not the world we live in. Most people carry bal

That would be true if all credit card customers pay their monthly bills in full, every month. However, that is not the world we live in. Most people carry balances a majority of the time, with interest rates significantly above "the cost of money". Further, the banks (really: card issuers) (in the US, at least), are collecting 0.5-4% of all transactions as fees.