Perhaps this is right - and I don't professionally taste wine, so your man should know better than I do - but from my own experience of sometimes drinking very good and very expensive wine, there really is a demonstrably worthwhile difference! My father, a lawyer, was once paid by a client with a case of good Château Margaux, including some excellent years ('82 and '85 in particular); we've drunk these together slowly over time, on special occasions for the most part, and they really have been phenomenal. I don't know what you could buy for $20 that would in any way compare with those bottles (which probably would sell for 20x that amount, if not more).
But, as they say in Latin, de gustibus non est disputandum. My mother and my wife detest the Margaux that my father and I enjoy so much - my mother charitably calling it "a man's wine" and my wife calling it... something much less charitable. But I think both of them would agree that it is certainly very different - in taste, colour, and bouquet, even if they can't actually enjoy those aspects of it - to what you could buy in a supermarket.
But, as they say in Latin, de gustibus non est disputandum. My mother and my wife detest the Margaux that my father and I enjoy so much - my mother charitably calling it "a man's wine" and my wife calling it... something much less charitable. But I think both of them would agree that it is certainly very different - in taste, colour, and bouquet, even if they can't actually enjoy those aspects of it - to what you could buy in a supermarket.