Fact 1: If you don’t keep several thousands of dollars in your checking account, overdrafting is near the only way your bank makes money on your account.
I thought the bank could make money by lending out a multiple of all the money deposited, such that if I deposit 1000 dollars, they can now lend out on the order of 30000 (i.e. thirty times) that. If they lend that out at, say, 10% interest, they can make 3000 a year because I have 1000 in my account.
The magic of fractional reserve banking. If I've misunderstood this, I'd very much like to be corrected, please.