But the only reason fentanyl is a prevalent recreational drug is prohibition.
Heavy users vastly prefer heroin, casual users much prefer oxy or similar. Fentanyl is just cheaper to obtain and easier to traffick.
Furthermore a lot of fentanyl deaths are caused by mislabeling and misidentification of the drugs which would not happen without prohibition. Fake painkiller pills with fent in them, fentanyl poorly mixed into heroin or filter, etc.
The difference between fentanyl and other drugs is a matter of degree.