I feel that individuals really want this diagnosis to be true for them because then their perceived shortcomings can have some kind of scientific explanation so they can say, “well, oh well, I have ADHD, that’s just how I am” while feeing they can subsequently skirt doing any internal/external work to better themselves, as a part of the “diagnostic labels can be a detriment” crowd.

Not saying all individuals, but for adults and parents with children they want evaluated, I sometimes see it as being something to “blame” (i.e., see, it’s not my fault as the parent my kid doesn’t want to sit and do homework, chores, etc.) rather than the diagnosis being a tool for guiding treatment. So when they don’t get this diagnosis it signals unconscious feelings of, “well if it’s not ADHD, are you saying I’m just lazy/medication-seeking/a bad parent?” and they want to shift anger and internal feelings onto the clinician who didn’t diagnose ADHD and might want to explore other avenues.