https://www.webmd.com/mental-health/addiction/news/20101101/...
Alcohol ranks very highly because of it's severe harmful effects on the body. However, behavioral effects tend to be those which make drug users a threat to society.
But cocaine's harm is highly dependent on its form. In some pre-Colombian civilizations, as well as in some parts of modern Colombia and Peru, drinking coca tea is/was quite common, and yet life carries on without serious problems. However, smoked and snorted cocaine tend to cause severe behavioral problems in a subset of users, and high doses of cocaine can cause heart attacks. Legalizing coca leaf/tea is an approach I've toyed with to significantly reduce the profit margin of drug trafficking (hopefully) without increasing the use parenteral cocaine too much.
This is also generally true of hard drugs like heroin and cocaine, but here I think the addictive qualities are what makes them a social problem.
What do you think happens if you take a low dose of marijuana or mushrooms?
You are stipulating that ethanol [0] is the only psychoactive substance which can be properly dosed for its effects? Sorry, but you realize that's rather.. uneducated? It's about potency, tolerance, bio-compatibility and the resulting individual threshold.
Case in point: Your "one or two" drinks could be beer, booze shots, cocktails, wine and many other products with varying, often not even labeled, potency. You could drink them over the course of 2 hours or 5 minutes, all of that influences the final effects, especially how regularly you are having your "only one or two drinks".
That's why there are such things as "functioning alcoholics" or people who regularly consume high potency cannabis and thus don't even notice any effects when consuming low potency cannabis.
Your anecdata is incorrect. I can smoke two bowls (or even two 1/8ths) in the course of say 45 minutes, and I will more sober than if I had two IIPAs or two shots of tequila.
That's a rather dishonest comparison to make. Alcohol consumption is very well recorded and tracked due to its legal nature, the same can't be said about cocaine, heroin and pretty much all the other illegal drugs.
For all we know addiction to illegal harder drugs might be far more widespread than most of us would ever like to admit. Especially considering the supposedly recent "opiate epidemic", where the line between "legal prescription use" and "illegal addiction use" doesn't really exist, it's rather fluid.
That's why it's dishonest to make comparisons along the lines of "If all the people drinking alcohol would instead be taking cocaine/heroine the situation would be worse" because nobody can say with any certainty how many of these people drinking are already also regular users of illegal drugs. It also doesn't say anything about responsible use, which exists for alcohol just like it does for cocaine and even heroin.
It might just be my anecdotal experience, but the vast majority of users, especially the responsible ones, are very rarely public about their use, even to friends and family. Usually, you only find out about their habit by accident or if you share a similar "hobby" and know what to look for.
It's a common misconception that illegal drug users all are easily spotted by their lack of body hygiene/low economic standing/whatever other myths the "War on Drugs" has spread to make the illegal stuff seem so much worse than the "good" legal stuff.
What is your definition of "harmful" here? Is it just total amount of harm caused, or total harm divided by number of users? If the former, sure, but I think that just reflects how hugely popular it is.
If the latter, I'd like to see your data. Some large fraction of the adult population consumes alcohol on a fairly regular basis so I imagine society would collapse if it was as harmful on a per capita basis as something like cocaine or heroin.