There must be some legitimate manufacture of it as well, and legitimate medical use.
When I broke my leg, four years ago, I remember that the paramedics gave me an injection of fentanyl before they undertook the difficult and delicate task of extracting me from the construction site where I had been working. I remember one of them saying the name “fentanyl” as what they were going to inject into me, and I remember realizing right away that that's the same drug that had been in the news quite a bit, over people dying from overdoses thereof.
I wasn't worried by it. No attempt was being made to get me “high” on it, and these were medical professionals who knew how to properly use this drug to control the pain that was going to be involved in moving someone with a broken bone out of a rough constructions site.