Below are two points I think people tend to overlook when thinking about alcoholism. It's only based on anecdotal evidence, but I happen to have better access to anecdotes about this matter than your average person. I would think the points also apply to other drugs, but I have no expertise concerning those.
1. When people learn that someone's an alcoholic, they are quick to ask what went wrong: Was he depressive? Lost his job? Did his wife die? Or is he just an all-around lowlife? Even if such explanations do not seem to apply, the legacy of Freudianism - not some deep appreciation of psychoanalysis, just the license to offer speculation about hidden motivations with zero evidence - ensures people feel free to speculate about deep-seated conflicts, a solution to which the drinker meant to provide (unconsciously, of course). Sure, it happens that people seek comfort in drink when something terrible happens to them, and some of them turn into full-blown alcoholics as a consequence. Others self-medicate against depression that has no obvious external root and get hooked. But the simple truth of the matter is that people differ enormoulsy in their ability to enjoy alcohol. If you don't like being drunk, you're never going to become an alcoholic. Many people get addicted to alcohol for the same reason that music lovers amass huge record collections: It just comes with the appreciation.
2. At least in this country, the health care system throws itself at drinkers as if the health care system were a fourteen-year-old boy and the drinker were a blonde with huge boobs, a miniscule skirt, and a questionable reputation. Average waiting time for rehab, according to my small sample from urban areas: less than a week. Cost: ten Euros a day, just like regular hospital stays (welfare recipients pay nought). And then there's self-help groups, anti-alcoholism NGOs, and whatnot. One might hence wonder why not more alcoholics seek treatment for their ailment which so obviously hurts them. There are extreme cases of addiction when people, it seems, have lost the ability to make choices like a regular person, but that's a minority. Now put yourself in the shoes of an addict who is fully capable of making choices and considers going into rehab to get rid of his addiction. Almost any alcohol addict would rather continue his current drinking levels without the addiction and the health and social consequences than with them. But that choice is not on the table. The choice is between current drinking levels with all the nasty consequences vs. getting rid of the nasty consequences and never being allowed to drink again. Ever! Again! If you're a real, serious music lover - the kind of person that owns thousands of records - imagine you could seriously improve your social functioning, life expectancy, etc., but would lose your ability to listen to music as part of the deal. That's not exactly what they call a no-brainer.
It's really the same point twice, innit?