I'm not a wine drinker, but I will say that wine from a box just seems ...........wrong.
Well, the advantage is not only that it's cheaper, but that theoretically you can have just one or two glasses at a time and because the wine is vacuum-packed (actually it's in a heavy plastic bag inside the box), it will last for a long time.
Though, as Lynne said, the opposite is likely to happen, too -- you drink more than you otherwise would without realizing it because you can't see how much you're getting.
Most of the wines I like start at $100 a bottle and go up in price.
I don't drink $100 wine, not only because I can't afford it but because I don't want to be exposed to it and find that's the only kind I like, too. I'd rather just be obliviously content with cheaper wine.