The fallacy that this entire discussion has been trapped into is the assumption that the selfish thing is to accept every transaction, no matter how small the fee is, rather that is altruistic.
Accepting every transaction is the selfish thing. Every batch from the oven yields an unlimited amount of bread. And there is a thousand people who offer to pay very little. Will the baker decline to take the money, throw away the bread and let the competitors make the sales instead?