This is no way disregards the difficulty of living with an actually severe case of ADHD but is not what most of these people are dealing with.
EDIT: many seem to have misunderstood what I mean by this. I’m not saying these people are only claiming to have ADHD to use it as an excuse. What I mean, is that they may very well do have, and they’re using it as an excuse. Mostly to themselves.
Someone not too long ago linked me to research saying self diagnosis at least for autism is, in adults, practically just as accurate as professional diagnosis.
Edit: also I’ve been self diagnosed as having synaesthesia since my early 20s, was later confirmed and I even participated in synaesthesia research as a subject for three different entities. So, I disagree with you, especially for mental stuff. There is a lot of room for error but from there to say self diagnosis is bs, that’s a stretch