In the US, doctors were prescribing opioids for pain medication for decades, ignoring the addictiveness and decreased effectiveness over time.

So someone who went in for surgery or had an injury could end up hooked on their pain meds… except the meds would become less and less effective over time, requiring larger and larger doses. Until the dose passed the “legal” threshold, at which point these people switched to illegal suppliers to survive. And eventually the doses got to be so large that their bodies couldn’t handle it, and they died.

And then there’s people who got hooked on methamphetamines because they were a cheap but effective way to stay up all night and study for an exam when they were a teenager— and eventually they couldn’t function without them.

And that’s just two common examples from two drug families, ignoring things like e-cigs (person gets hooked on something they didn’t even know they were consuming), regular cigarettes, or alcohol, all of which are legal but can also be addictive and deadly.