Once upon a time life was simple. We had to fight for survival, had only time for hunting/gathering and procreation. Very simple, a female coupled with a male and got as a result offspring.
For as yet not completely understood reasons ( best theory for beta males not to be attacked by alpha males) bi/homosexuality became a survival trait and the trait withstood evolution.
Nowadays we are free from the fight for survival in some nations, too much free time on our hands so a new generation has been generated which overestimate their own importance. Searching for grounds to support their entitlement there is group that tries to justify their ‘uniqueness’ by building on the simple principle of 2 genders that procreate to keep the species from going extinct to some inexplicable notion that genders don’t exist but that there is a spectrum of genders.
Obviously this has to be added to the upcoming redaction of the DSM since it has no basis in reality but a lot in abnormal psychology. Can be put somewhere with personality disorder.
That the person in question imagines they are in a gender spectrum doesn’t mean such a spectrum actually exists. And by the intense media attention given many an impressionable person will easily be convinced that he/she/it also has this disorder.