If I said to you i'm a 1000 year old reincarnation of a furry telekinetic otherkin alien from a transdimensional future where everybody is the size of skyscrapers, would you accept that? That's what I define myself as, so that's what I am?
Yet you can clearly tell I am not that, and in fact never shall be.
Maybe I just like to operate within the bounds of reality, at least when it comes to reality. If I want to be a said skyscraping alien I always have fiction to turn to - but that's the point, it's fiction.
See, there's the thing. Everybody has unrealistic self-perceptions of themselves - some are achievable, some are not. Those things that can never happen are confined to escapism or abandoned altogether - no truly healthy person can keep these aspirations ane believe them achievable. A man cannot become a woman, a woman cannot become a man - this is the truth, yet people mistakenly believe that we live in a society where such a transformation can be done; it can't be done, not genuinely, at least not yet.
Trans people who live vicariously through fiction and video games are fine, but when they bring this attitude into their real self, things get literally ugly.