The discount for the big banks amounts to somewhere in the neighborhood of 80 billion dollars a year. That also is the amount of profit the banks make in a year.
Think about it.
Not only are the banks insured against bankruptcy by the American people, they are, by the reckless behavior the government insures them from the consequences of, producing a regular series of economic catastrophes.
Their banking skill, knowledge, expertise, their profit, is entirely a matter of getting from the American government the insurance that allows them to go on year after year wrecking the economy.