https://news.ycombinator.com/item?id=13847136
IMHO Marijuana isn't a relevant example for the parent's argument because it's not that dangerous; it still is distributed illegally except for a few states in the U.S. and parts of Europe, and (almost) nobody dies from marijuana overdoses.
opioids, especially the lower potency ones, do not meet this criteria at all. With tolerance, minimum effective dose increases, but so does the lethal dose. With pharmaceutical-grade opioids whose amounts are precisely metered, it's possible to live in that window.
It's only opioids under prohibition (aka, uncertain/varying doses and ingredients) that are inherently dangerous.
There is no place in the US where traffic in marijuana is legal. The absence of state-level prohibition doesn't negate federal prohibition.
That's how a couple of people in my rehab ministry died. Meth is more reliably predictable in comparison.