ADHD is a cognitive disorder of executing functioning. Its original name was "minimal brain dysfunction". It has little to do with how you feel, and most to do with how you function. It is easy to demonstrate with cognitive tests. It is now getting easy to demonstrate with brain scans.

Do you doubt the existence of autism? Dyslexia?

Probably not.

Sorry that it can't play the role in your polemic that you were hoping for.