People can 'believe' what they wish. In this instance they are profoundly and demonstratably wrong. And affirming that wrong belief is doing them absolutely no favours. Witness the response to their finally having been told 'no'.
A strongly-held belief in a reality that isn't real, that we are something which we are patently not, is a delusion. Sometimes the delusion is a primary symptom; at others, it's a secondary symptom of another underlying mental health disorder, often of the variety involving a disassociation from reality.
Either way, 'affirmation' is far from being the cure. Anorexics suffer from bodily dysphoria: the delusion that, no matter what their body shape, they are fat. We don't affirm that delusion by agreeing with them that they are fat and facilitating the starving of themselves to accord with the bodily image they perceive. We give them mental health support.
Erotomania - the absolute, unshakeable conviction that the object of the erotomanic fixation loves them in return - is another such delusion which in fact provides an interesting parallel with trans activism. Even if the object of desire is a celebrity, or someone unknown to the erotomanic, their every word or deed is perceived as confirmation of this 'love'.
The erotomanic doesn't have the legal right to stalk the object of his (it's usually a 'he') affections, to close that gap between presence and absence, to make his unwanted presence felt every day through his unwanted contact. There are legal measures in place to prohibit this. Same as the presence of males in a female changing facility is unwanted contact (and if one woman says 'no', she has the veto. Other women do not have the right to consent for me).
Stalking, the frequent manifestation of erotomania, is quite rightly a criminal offence. It's a gross invasion of another person's boundaries, without their consent and where contact/boundary overstepping is unwanted.
Erotomania, stalking and recent demonstrations of TRAs' behaviour are all driven by the delusional belief - or pretensions to such a belief - that reality doesn't exist the way it truly is and that other peoples' boundaries can be completely discounted as a means of affirming that delusion.
Too much 'affirmation', and for far too long, is exactly what has led to last week's outcome.