Presumably you start with other drugs and especially weaker opiates. E.g. painkillers in pill form might be relatively harmless (compared to Fentanyl of course) but are more expensive and harder to get especially after the crackdown on prescriptions.

Fentanyl OTH seems to have a great cost/“value” ratio so when you’re already addicted and can’t afford anything else you don’t really have much of a choice. At that point your description of Fentanyl users is probably accurate but there is a long road to get there for most.

Also let’s be fair, it’s not like some European countries don’t have serious problems with drug related deaths (even if on a much smaller scale overall). Scandinavian countries all especially bad in that regard (Sweden has the highest number of deaths per capita though Finland and Norway are not that far behind). They are just much better at sweeping these problems under the rug because it’s not as visible (no homeless people).