When the article is less sensationalist, HN often expresses an interest in stories about drug addiction.

I can see a couple of reasons for this.

First, there seems to be a prevailing view here is that the war on drugs is an abject failure.

Furthermore, I believe addiction gets attention here as a fascinating scientific puzzle, whose questions and answers are deeply involved with philosophical issues such as free will and the nature of desire.

This is probably why the article made it as far up as it did on HN.