That’s really a misunderstanding, commonly repeated even by professionals but not really scientifically valid.
There are a lot of different causes / paradigms / regimes for ADHD that all get lumped into “ADHD”. Various therapies have hugely different effects on different types of ADHD.
And some ADHD drugs tend to have the same effects on non-ADHD people as they do on ADHD people.
Here is an (also outdated) breakdown of 7 types of ADHD that are differentiable using brain scans: https://neuropedia.com/7-types-of-adhd/ Each show different parts of the brain affected. The "ring of fire" type of ADHD is notable for responding very poorly to stimulants.
