You are making the mistake of assuming that they can deliver a package cheaper than their competitors. All they have done so far is show their system can deliver that package for less cost than their competitors charge, which includes a profit margin. If they start competing for outside business they will want some profit margin. How much? I don’t know, but compared to their cash cow cloud business, it would be abysmal. At some point Amazon will decide if the delivery business is helping improve the bottom line or should be spun off. Not my circus or monkeys, should be entertaining to watch.