Whom gets to decide and determine who is “most vulnerable”?
Also when it comes to the Nordic countries it’s rather hypothetical, considering that they (+Estonia) have one of the highest rates of drug overdose related deaths in the EU. Surely they would have adopted different policies on that already if their goal was protecting the most vulnerable rather than puritanical moralism?
Also while you might have a point in principle it has quite little to do with random chance like in the Russian Roulette example.