For example, I'll get flyers in the mail offering mortgages for an absurdly low teaser interest rate for the first year, and after the first year the interest r

For example, I'll get flyers in the mail offering mortgages for an absurdly low teaser interest rate for the first year, and after the first year the interest rate goes above market. I carefully read the contract. If there's no prepayment penalty, I'll get the loan. A year later, I refinance and pay off the first mortgager. I asked my loan officer "why do they do these contracts?" He laughed and replied they were playing the odds - the vast majority of people are too lazy to refinance, or didn't read the contract. Once I bought a new car, and they offered 0% financing after we agreed on a price. I asked, why would they offer 0% financing? The dealer said the terms of the contract were if you are late on a payment, you get hammered with interest. I said sure, I'll take the loan, and set up an automatic payment plan. This is all basic stuff. The credit card thing is mostly just for practice.