The long answer is that this is a controversial issue even among trans people.

There was a large group of influential thinkers known as post-structuralists who were critical of things being spoken about in absolute terms. They argued that most things were in a state of constant flux, and a lot of them were very heavily overlapping with the anti-psychiatry movement. They thought that psychiatry was primarily a tool used to say that some brains were good while other brains were bad, and that the purpose of trying to diagnose and treat mental illness had more to do with social norms and increasing the power of state and capital. The post-structuralists continue to be very influential to modern day queer theorists who often argue that pathologizing gender dysphoria stigmatizes trans people and naturalizes gender roles which they believe to be socially constructed.

Other trans people believe that there might be some biological tendencies in the brain that differentiate between the sexes. They argue that hormones and surgery can help alleviate this sort of innate disconnect between body and mind. They're less concerned with gender roles than they are with the idea that dysphoria is a painful experience but hormones work. They often want to keep gender dysphoria listed in the DSM as a mental illness because if it weren't it wouldn't be covered by insurance plans.