I don't need to read some guy's book or watch random videos when I can read peer-reviewed, published medical papers. You're misunderstanding the role of genetics in brain development. From birth, the ADHD brain begins developing differently. In the presence of childhood trauma, often exacerbated by ADHD itself, the brain's development diverges even further.
Your worldview fails to account for genetic, environmental and sociological effects on brain development, and you seem to think that someone can just will their brain to suddenly develop more dopamine receptors and better neurological dopamine regulation systems.
Please read the book. The genetics are accounted for as are all other biopsychosocial factors that correlate with a lot of metabolic and mental illnesses.
Your worldview fails to account for genetic, environmental and sociological effects on brain development, and you seem to think that someone can just will their brain to suddenly develop more dopamine receptors and better neurological dopamine regulation systems.