Marginal cost is often not a good way to evaluate things. A person who focuses only on marginal cost will say "It only took you an hour to make that" while dis

Marginal cost is often not a good way to evaluate things. A person who focuses only on marginal cost will say "It only took you an hour to make that" while discounting the decades of training it took to be able to. A person who focuses only on marginal cost will say "I could have made this at home" while discounting the reasons why they didn't. Prices relate to provided value, not just cost.