Transgenderism

Why does such an obvious mental illness get so normalized, by one political party in particular?

I mean, look at something like alien hand syndrome, which is imagining that part or all of one of your limbs doesn't belong to you. Or body integrity identity disorder, which is imagining that you have a physical disability. There's also Copen's syndrome, which is a mental disorder where you imagine that you're a dead body.

Those are actual real mental disorders. (Look them up.) And they seem rather similar to transgenderism. Yet there's no effort to normalize those things like there is with transgenderism.