Except ADHD is not even a fictional illness because it’s not an illness at all, it’s a disorder, it’s right there in the name.
To be the devils advocate, there have been plenty of researchers and psychotherapists in the recent decades lamenting ADHD as too broad a diagnosis, and it has indeed been scrutinized on multiple occasions as a convenient way to sell prescriptions.
As someone diagnosed with ADHD, depression, and nerve pain, I’d take ADHD and depression over nerve pain any day, they’re not even in the same camp, and clearly not even in the same camp as cancer.