Meh, I'm on the fence with considering addiction a disease. While there is a genetic component, unless you activate the gene there is no problem. I liken it to type 2 Diabetes, which in most of the people diagnosed with it is actually not a disease. Until it progresses to the point where the beta cells of your pancreas die it is mostly a reversible metabolic state. Remove the environmental factor(s) causing the specific genes to be activated and the person returns to normal.
While I certainly would not make light of either an addict or a diabetic's health issues, I also refuse to completely ignore the fact that free will does exist and they elect to do things that are not in their own self-interest. IMO, this is as much a cultural issue than anything else. Americans don't think they should delay gratification, so they take the short-term reward of getting fucked up or eating something terrible for them rather than abstain and achieve good health. And this is coming from someone who used to have a couple of beers every day and still takes the pot.