I wasn't drugged in childhood (other than paracetamol?) and ADHD made adult life incredibly difficult until I started medication. Now it feels like adult life is easy, and I can't believe it is so easy for other people. N=1 but not being drugged didn't prevent ADHD for me.
I don't think we have good data about this because the prevalence of adult ADHD diagnosis will vary a lot between countries for cultural reasons or because of differences in distributions of careers, even if the underlying level of adult ADHD does not vary.