That depends on drugs. If you hook people on highly addictive expensive drug with severe withdrawal symptoms, like heroin, it naturally spawns more crime, because addicts would resort to anything to get the next doze: theft, robbery, prostitution, murder, etc.

People hook themselves up, not other people, who may help do so, but the person taking drugs is the one responsible.

I think you misunderstand how this works in reality. Nobody walks to a shady oerson standing near the corner and says, "hi, I'm joe, today i want to try this meth stuff I've been hearing about, how much for a dose?" When a person is in a vulnerable state, there is always a 'friend' who offers first dose for free, and says, that it is ok and totally safe to try a few times. Consequences come later when it is too late.

Opioids are added to less addictive drugs to make the customer more regular and thus drive more profit. It's never smart business to kill your customer but it's also not smart business to have a customer that only texts once every few months.