Competition can mean rivalry or freedom. All firms must serve the preferences of consumers in order to exist. Monopoly has historically been an artificial privilege granted by the state.
Monopolies do not last for long in free markets unless maintained by government interventions. Antitrust policies were generally not demanded by consumers, but created by jealous competitors. Antitrust laws are insensible and wasteful.
The eighth in a series of ten lectures, from Fundamentals of Economic Analysis: A Causal-Realist Approach.