People Talk About This As If It's Real

 From the AI:

Gender identity is a person's internal sense of their gender, which can be male, female, or something else. It can also be described as a person's sense of being a woman, a man, both, neither, or anywhere along the gender spectrum

Maybe some people have this, I don't.  I don't have some internal sense of my gender, I am a man and I recognize this because it happens to be true.  I have an internal sense of being but it isn't gendered, it's just existence and awareness.  It's tempting to call the whole concept a myth, but I can be charitable and trust that some people report having such an identity.  By it's nature, it cannot be measured in any way other than asking a person if they have such an "identity".  And who knows, on reflection, maybe most people are like me.

If I woke up one fine morning and was a woman, I would start thinking of myself as a woman.  There have been 62 years of life as a male and so I certainly would have to learn a lot about navigating the new reality.  I might not like the situation but would recognize that it was, in fact, the situation.