There's something in this but I don't think it's quite that simple, there are plenty of unhappy people in many countries. My friend's wife is Italian, he's gone out with her and her friends and was struck by how little booze they drank and thought it was very civilised, she pointed out that Italians are so obsessed with their appearance that they won't become drunk, so it's a different form of uptightness. Yanks, Aussies and Kiwis drink similar amounts to us, or in the same way - drinking to get drunk, you could say they've inherited our culture, which is largely true, especially Oz and NZ. British drinking is nothing compared to Eastern Europeans or Russians, that said they have our issues magnified: worse winters and greater poverty and inequality. A Ukranian friend said very good quality vodka is (relatively) cheap there and believes the price is kept down to keep the populace docile, maybe there's something in that.
People have always taken substances that have some sort of physical or psychoactive effect, caffeine and tobacco are big hits around the world, as well as booze, not to mention all manner of (mostly illegal) drugs. Many (all?) indigenous cultures manage to find some sort of plant,fungi or even animal that has some sort of psychological effect. I think humans are too intelligent, we bore easily and are prone to anxiety and depression because we know we, and other people we care about will die, and we can imagine negative futures (a mostly useful evolutionary trait - in terms of planning etc), so we need safety valves.