I have been diagnosed with ADHD and to me it really has been great getting treatment. I think it's unfair to blame everything on ADHD and not take responsibility for anything but for me where I think it's different from someone who doesn't have it is that I was unable to pay attention during lectures for example. Like I really wanted to and the information was still interesting but I still couldn't get myself to pay attention and that caused a lot of anxiety and severely effected my self esteem since I was blaming myself and saying "well you just didn't try hard enough" and things like that. Like most things, ADHD is a spectrum so there is likely a lot of it that goes undiagnosed. A lot of the symptoms are pretty normal human traits but I think how much those traits are present is the big thing.