In medicine, you have two ways you can go about your job. You can care and get in touch with every patient and most times their deaths will hit you no differently than a friend. Or, you can look at them as objectively as you possibly can, not letting feelings or emotions get in the way of your diagnosis and treat them as effectively as possible.
Very rarely is there a true median between the two.
I would wager that a person who works with drug addicts sees it as such, "There are thousands dying of cancer, genetic birth defects, Parkinson's, Huntington's, etc. and these people willingly chose to take drugs at some point. A self inflicted disease does not deserve our treatment when we could be helping so many that had no choice in their affliction."
But that's just me. Generally you don't get cynical just waking up in the morning. It takes years of seeing things to get jaded to the point to have a belief like that, and to say its wrong because he has a different view of yours (one that he feels is valid, and he is right that it is) is less empathetic than his words that it's just another dead junkie.