It’s definitely under diagnosed. 5% of the world population is thought to have ADHD. I know plenty of people around me that show serious signs of it and they have no idea. Granted I’m not a psychiatrist, but I live with an ADHD person and the similarities are striking.
Absolutely not, the tricky thing about ADHD is that it’s mostly lots of small things that everyone has or does. (Bad short term memory, executive dysfunction, rejection sensitivity, inattention, difficulty to focus, etc). People with ADHD have a lot of them all at once and that’s the problem. It’s a spectrum with a threshold of issues to have at once to be considered ADHD. That’s why it’s not easy to diagnose, it can vary wildly from person to person.
I do believe that’s a paradoxical statement considering where you made it.