My brother didn't get medication either - he is a drug addict. He self- medicated. He also can't support himself. He is going to be 60. He did get married but then went bankrupt . She divorced him. They never had kids. Now he is totally beyond repair. He gets SSDI and can't manage to live on it. If he had had meds, he might be married with grown children. Who knows. Kids who don't get meds are much more likely to self-medicate later I think.
ADHD kids are automatically more easily seduced by dangerous things - for me it was extreme sports - for my brother drugs. (lucky me). They are also more impulsive and don't think through consequences. When I think of all the things I did as a kid and young adult - I am SHOCKED that I lived to tell about any of it.