If I got diagnosed 10 or 20 years earlier, I wouldn't have dropped out of university and my life would have been profoundly different and better.
Extreme ADHD is a constantly shifting quest for volatile stimulation. This results in poor diet (extreme sugar cravings all the time), short term memory loss, failure to achieve basic tasks, obsessive behaviors, poor social framing, and more. For these extreme cases medication provides clarity that allows for more rational control of basic cognitive decisions.
I suffer from ADHD, probably-- enough that I wrote a book about how I couldn't abide school and can't force my brain to think about arbitrary things. I developed ways of dealing with it. I don't want to take any drugs for it, because I like being me and it is part of me.