The Austrians view is that monopoly came about as privilege, usually granted by royalty, given to a particular person or industry. This process is arbitrary and capricious. Free entry is required in capitalism. There cannot be restrictions on entry, as with doctors.
Price, quantity, profit, and deadweight loss are four criticisms of monopolies.
Lecture 9 of 10 from Walter Block's Radical Austrianism, Radical Libertarianism.