There are 2 kinds of monopolies
1 kind where the monopoly is created by the free market
and the 2 kind where it is created by the government by using patents
the free market monopoly, even if it is a monopoly it sells at a low price because they want to be a monopoly
even sometimes they lose money to kill their opposition, that creates cheaper goods for the consumer
the monopoly created by patents makes the price as much as they want, no one is going to compete with them, they cant compete
take medicine creation as an example Daraprim to be exact the guy has a monopoly and the price is 750 per tablet