I am going to admit that I did not read this entire piece but from what I did read, it's a comprehensive look at why fentanyl is such a hard drug to stop, from an import standpoint.
We bought what’s needed to make millions of fentanyl pills–for $3,600
Reuters penetrated the illicit fentanyl trade, buying chemicals and gear online to make millions of pills. Cost: $3,600. Why the opioid crisis is so hard to stop
reuters.com