Not a doctor. Not an expert on trans people. Just my layman observation.Gender dysphoria is definitely a mental condition. I’d stop short of calling it alone a disorder in this day and age based on melding of gender roles in modern families.Let’s assume for purposes of discussion it is a mental illness.
Do you discard others in your family with other types of mental illness? Question whether it’s legit? Tell them to suck it up, don’t be a wuss?
At the level of sexual reassignment surgery, it is a complete incongruence of a human being's psychological and biological existences, culminating in a refusal to accept their physical genetic makeup, changing physical appearance to become the opposite sex with modern surgical procedures and pharmaceuticals. I understand why some people consider this a disorder.