Just let ‘em die?
The number of people who play Russian Roulette is very small. Sure, once in a while someone will, and it won't go well. But most people avoid that game because the odds are very bad and the potential cost is very great.
Drugs like Fentanyl are "more fun" and "less risky" and so lots, and lots, and lots of people dip their toes in those waters. I would like street drug to be more like Russian Roulette because I want fewer people to dip their toes in those waters.