I think you're veering too far into prescriptive territory here. Yes, most people can't tell the difference between good wine and great wine in double-blind taste tests, but almost nobody ever drinks wine in double-blind conditions. Generally when you're drinking great expensive wine you know that it is expensive, and you enjoy it more as a result. Psychological effects are real effects when we're talking about how much enjoyment people derive from things.

And by the way, the poor absolutely are not drinking $20 bottles of wine. Alcohol consumption is significantly higher in the rich than in the impoverished, because when you struggle with putting food on the table everyday and keeping a roof over your head, any kind of alcohol is a luxury. I don't think you really know how bad it is for lots of people. A large number of Americans don't even get the choice between $20 and $200 wine.