Water is essential,but the marginal benefit of an extra cup is small because water is plentiful. By contrast,no one needs diamonds to survive,but because diamonds are so rare,people consider the marginal benefit of an extra diamond to be large.
Water is essential,but the marginal benefit of an extra cup is small because water is plentiful. By contrast,no one needs diamonds to survive,but because diamonds are so rare,people consider the marginal benefit of an extra diamond to be large.