Your fundamental belief that addiction is a disease is a big mistake. Addiction is a series of decisions, nothing more. You cannot possibly compare a series of personal decisions to something like leukemia or any other actual disease.
When someone is ready to stop doing something, they stop doing it.
When someone is ready to stop having cancer…well, guess what? They still have it.
See the difference here?
There is a huge industry created around making people believe that they have no control over themselves. This kind of thinking (especially when promoted for monetary gain) is what is destroying many lives. Not some plants that mankind has used for many purposes since time immemorial.