Is patented technology a monopoly? Is the patent fee set by the patentee himself? !

It can be regarded as a monopoly, but it is a legal monopoly. Where national interests or major social interests are involved, the state will restrict monopoly, such as drugs for preventing or treating infectious diseases.

The patent license fee can be set by the patentee himself, but only if the other party is willing to pay for it. For example, if your patent itself is worth 1 10,000, and you want others to pay 1 10,000 or the right to use it, people will not make money after using it, so naturally they will not buy it.