Drunk driving should not be a felony, it is a problem for medicare.
Addiction is indeed a medical problem, i.e., a disease, and one with out a medical solution.
And, although you/we would jail or execute a mentally ill person under some circumstances, and jail a mentally impaired drug user, there needs to be a better way. Drug avoidance can be made a matter of morality; we can punish some in hopes of deterring others. But, once addiction sets in, the person's ability to choose effectively is compromised.
Consider the most physiologically addictive behavior of all: sex. How many people successfully avoid that in their youth? How many more claim to but in fact do not, and spend a lifetime addicted to non-normal sexual behavior and lifestyles? Plenty. There is the proof of how addiction can distort will and personality.
The brain is altered, possibly 'rewired' by addiction; what better word than 'disease' is there to describe that?