You're right, you don't get to decide. Scientific data is the deciding factor and it's been proven and medically documented as a Mental Disorder. You not wanting to admit it because you somehow think that everyone that agree's with it being a disorder is somehow equivalent to them looking down on someone or treating them differently that's suffering from it, does not change that indisputable fact that it is a Mental Disorder. No one is attacking trans people or looking down on them in this thread topic.

You're doing it right now by insisting that it must be a mental disorder, when again, you cannot make that call for everyone else. Nobody can.

The only reason that people would cling to this terminology is to have something to lord over trans people and make them feel like there's something wrong with their heads.