oh sure, this is about moderate drinkers, not about people abusing alcohol as a drug. The side effects of moderate use of pretty much every controlled substance are pretty much insignificant as long as you use a pure, unadultered drug (let's forget about croc or battery acid etc). But once you get into heavy use, alcohol starts looking pretty bad: destroys liver and brain among other things, compared to e.g. opium where the worst side effect is constipation. Overdoses obviously kill in both cases, so let's keep that out of the picture here.

Withdrawal from alcohol can literally kill you[0]. Withdrawal from opiates can also cause similar withdrawal symptoms, but is not fatal[1].

There are many ways to judge the statement 'most harmful drug', so there's no bright line, but that's a pretty big mark against alcohol.

[0] https://en.wikipedia.org/wiki/Delerium_tremens [1] Ibid.

I think there are a few examples of tripping being the result of poisoning. Mushrooms, various cacti...

The reason mescalin makes you puke is not because it does a body good.