"Has unequivocally been proven." Totally on board with the promulgations of contemporary medicine. OK.
I think the 'disease' paradigm for addiction is interpreted and often not very useful. In the very least debatable and evolving. If it is a disease, then it is psychological interlaced with physical corollaries in which decision making plays a role, for example, to pick up, to not pick up, to seek therapy or no, to try anything new or not. There is an interplay between chemistry, anatomy and the freedom of choice you describe. Free will may be debatable, but it's very clear that even as a binge drinker, I am intimately experiencing a decision-making process that either feeds into a debatably diseased outlook or ameliorates that outlook.
It has also been unequivocally proven that cancer has a physiological and environmental ontology, although sure, quacks often like to point to some kind of underlying attitude problem, but that doesn't hold up. Nice slight of hand, but I'm not buying.