Sociologists. The literature on this topic in sociology is overwhelming devoted to demonstrating that addiction is merely a story people tell about drug use. As Kelley said, "drug" itself is also said to be a mere story. The topic is almost completely dominated by extreme "social constructionist" dogma. The researchers are so convinced that this is the proper framework, they literally never bother to look at the biology involved.
One of the other ill effects of the sociological schtick on drugs is that it has done away with an historical perspective on the trends involved. The most you get is some cockamamie backstory about how prohibitionist cooked up the addiction "story." Consequently, something incredibly powerful and loaded with powerful research questions like David Courtwright's _Forces of Habit_ gets walled off and ignored.
Meanwhile, if you don't think drugs are fucking people up, what can I say? Existing patterns of nicotine, alcohol, and illegal substance use are just fine with you? Junkies would be happy and healthy folks, if we'd just give them clean needles and livable stipends? I suppose this is consistent with your misanthropy. It is inconsistent with material reality.