I think the definition of a monopolist or someone who has market power is that you as a consumer don't have any choice. To give one example, a personal example, recently Venmo, which is a product I use as a consumer, said that they were changing their contract terms in their user agreement with consumers. They said that they were instituting mandatory arbitration clauses so that you couldn't join a class action lawsuit if you had an issue with them. The only way you could opt out of that is to mail them a written letter within 30 days. They also said that it wouldn't have any effect on future agreements they do and, if they decided to change those terms in the future, the only way you could opt out is to stop using the platform altogether.
These kinds of “choices” are not true choices. They are power asymmetries in markets. Increasingly, consumers, workers and small businesses don't have the option to go elsewhere because markets have concentrated to such a degree across different industries.