Gender dysphoria, the psychological suffering caused by feeling like you are in the wrong body, is the disease. Being a trans person is not a disease, and using that as a basis for insulting or discriminating is inappropriate. Somewhat like autism is the mental disease but having autism is not a disease and it is inappropriate to treat a person as if it is the entirety of their existence. Way too often illness has been used as the basis of mistreatment and outright extermination. People have diseases, they aren’t their diseases. We have introduced this notion from the fields of ethics in medicine and it’s why a lot of things are no longer used in language nor in concept: the disabled, the retarded, the syphilitic, the autistic, etc. People aren’t diseases and they aren’t their disease.

If you knew a thing or two about the history of gender, you’d know that medicalization of gender is precisely one of the main historical roots to justify discrimination, criminalization and abuse towards trans people. Medicalization of gender has literally killed millions of people throughout history.