Authoritative voice from the distant past - Sir Humphrey Rolleston:
The key conclusions of the Rolleston Committee Report (1926) in UK are worth considering (again, still) today. "[Addiction] in most well-established cases must be regarded as a manifestation of disease and not as a mere form of vicious indulgence. In other words, the drug is taken in such cases not for the purpose obtaining positive pleasure, but in order to relieve a morbid and overpowering craving. ... It is true that there is a certain group who take the drugs in the first instance for the sake of a new and pleasurable sensation ... But even among these a morbid need for the drug is acquired and the use is maintained not so much from the original motive as because of the craving created by its use."
To see the article.