Because you don't know how to argue without calling people Terf's and claiming the moral high ground as your total argument and this is no longer my problem to solve.
The complete picture of who we are consists of two things. Who we are and what we want to be.
Only with transgenderism does it manifest as this weird, line straddling "What I want to be IS what I am" way.
Being 5 foot 5 but WANTING to be 6 foot doesn't make you sorta 6 foot or a kind of 6 foot or 6 foot in certain situations.
When I close my eyes and picture "myself" I don't see exactly what the real world sees. This is true for everybody and there is absolutely nothing wrong with. Only with transgenders do we expect it to matter in this specific way.
Keep pretending it's super hard to understand because you can't function in an argument without a softball opponent you can call and Terf and wipe your hands of.
Technically, it's more than three. When we're talking psychological identity, it's three core elements: How we perceive ourselves, how we believe other people perceive us, and how we wish for others to perceive us. Note that in this context, "perceive" incorporates both somatic and psychological attributes. It's not just how we perceive our bodies, how we believe others perceive our bodies, and how we want others to perceive our bodies. It's also the content of our character. For example, TG seems to clearly want all of us to perceive them as being a noble, caring person willing to fight for what's right, and to stand up to injustice. Unfortunately for TG, as well as all other humans... how people actually perceive us (both somatically and psychologically) is beyond our control. I certainly don't perceive TG to be any of those character attributes listed.
Both the somatic and the psychological aspects of that identity are correlated with mental health disorders where the desire and the reality are out of alignment. On the somatic side, one of the most obvious examples is eating disorders, particularly anorexia. The patient perceives themselves to be fat; they believe that other people perceive them to be fat; they wish for others to perceive them as thin and fit. In reality, however, other people perceive them as being dangerously and unhealthily skinny. That departure from reality is a hallmark of the disorder. On the psychological side, you get into the various disorders that involve an element of delusion. That includes of course schizophrenia and psychosis, but it's also an element of both bipolar disorder and borderline personality disorder.
There's another aspect to identity however, that being objective identity as opposed to psychological identity. This is the means by which other people recognize you and verify that you are you. This is very largely based on our physical attributes, because nobody can read your mind. Think of the items on your drivers license or passport. For people who know you well, it can also incorporate particular behaviors. And in some cases, it will incorporate things like manner of speaking. For example, there are some authors who have a very particular and recognizable "voice" - their style of writing is highly unique, and is something by which many people would recognize them. Similarly, there are some singers or actors who have unique vocal characteristics that make their voices identifiable characteristics.
Part of the frustration with the current transgender activism is the conflation of these two different types of identities. It's the push for everyone to accept the individual's psychological construct of themselves... over and above our actual perceptions of them, and in contradiction to objective identifiers.