As a father to 3 successful, well adjusted men and a teenage boy I can tell you that (including myself when i was young), we were all told we ad adhd at some point.  
Its a bullshit, made up condition to get your kid on some life long prescription.  I do think that these MDs believe what they’re saying, but the schools they went to are all subsidized by big pharma.  A sick kid is worth millions over their lifetime if they’re on daily meds.
Incentive theory. 

“Show me the incentive, I’ll show you the outcome.” -Charlie Munger