There's a decision of the German high court finding there's no inalienable right to get high. However, the right to an education is a fundamental human right.
I'm not saying I understand or agree with the fundamental arguments. In fact, I don't think there aren't any arguments that were not subjective.
I'd say moderate intoxication is not a necessary evil. School is, though. Well, mild intoxication, for lack of a better word, is inavoidable. School is avoidable though.
Speaking from personal experience I find drug use and learning can be at odds very much. The topics are interrelated. And your comparison is backwards. If you are really saying: There can be good reasons not to go to college, but these don't generalize--whatever reasons those may be; Then we can prohibit drug use, if we can make school compulsory. There's no equivalence.
I mean how ridiculuous would it sound that, we must get these people high!? We must let them have relieve at the cost of a few failed existences--sounds not much better. It's OK in case of college, because we need that to reduce the need for it--something like that, if not to cure alzheimer. At this point I note that my idea of drug use chiefly to get high might strike someone as odd and in need of regulation.
That's what they call for, after all, control, information, responsibility. What would that look like in practice? Only one way to find out, you have to inform yourself.
The message that it's bad and hence illegal is therefore the simplest. It does not incur any further responsibility for the emitter, but leaves it completely with the user: It incures duty in prisons--that's the users fault, they didn't have to. Prohibition is a reasonable form of control, too. Because, first those who must participate will find a way any way, whether to their own detriment or not. And then, getting caught should always follow a prior fuck up. Import a substance that sells at the price of, I don't know, alluminum, although it's literally peanuts--hell yeah you are morally corrupt. And I don't see the price coming down after legilization. Whereas getting imprisoned for possession is rather difficult where I'm from, so it's a proxy for worse offenses that get one in the spotlight, often enough.
Perhaps price is a measure of control. If time is money, then an economist sees a lot of time going to waste; perhaps even in colleges and business schools. Thereby I've achieved reduction ad absurdum, commiting to the same falacious comparison as you.
If there's anything else I wanted to say, could have or should've said, the I forgot. My memory is very bad, sorry. I blame information technology, and a sped up aging process.