On a serious note, there are obvious risks involved in drug abuse. Drowning in water or vomit are amongst them.
Heroin withdrawal also has a risk of passing out and drowning, so the withdrawal process does come with a “no swimming” chit.
Even alcohol service has certain risks, and people who sell alcohol (in some countries at least) have to be trained in Responsible Service of Alcohol or equivalent. If a hotel serves someone too much alcohol and they exit the premises and get run over trying to cross the street, t(e hotel can be sued (in some places at least).
“Doctors” selling drugs of addiction illegally are generally not known for caring about patient welfare though. Just as with any other illegal drug dealers. People who deal drugs or profit off any addiction (including gambling) don’t care about their customers, they only care about the money.
