Opiates and amphetamines seem like they obviously have a different risk profile (and resultant societal impact) than nicotine or caffeine. Somewhat off topic, but I’ve always wondered if alcohol would still be legal if it wasn’t grandfathered in by, like, every single culture ever.

Nah. Opiates and amphetamines don’t kill 50% of their users. Nicotine does.

Except a few large ones :)