The American Psychiatric Association refers to it as a mental disorder. All scientific evidence points to the same thing. 41% of transgender people attempt suicide. If we don't take care of our mental health, a lot of transgender people are going to die of suicide. We can't afford to pretend it's not a mental disorder when so much is at stake.
Can you point to where the NCAA says it allows people to compete in the opposite gender that they legally belong to? There must be a specific bylaw, right?