What is one reason a competitive monopolist’s profit-maximizing price is not socially optimal?

The profit-maximizing price set by a competitive monopolist is not socially optimal primarily because they restrict production to enhance their profits. In a competitive market, the social optimum occurs where the quantity produced is equal to the quantity demanded at the price where marginal cost equals marginal benefit to consumers. However, a monopolist reduces output below this optimal level to raise prices and maximize its profits. This restriction leads to a deadweight loss to society, as potential gains from trade are not realized between consumers who value the product more than its marginal cost but are unable to purchase it due to the higher price.

By limiting production, the monopolist generates higher profits at the expense of overall welfare, illustrating the inefficiency created by monopolistic practices compared to a competitive market where resources are more effectively allocated.