Why do most people buy wine?

OK - you aren’t interested in the functional reasons why people buy wine. In my opinion these reasons are 99% of the answer to the question.

The answer you seek are the peripheral reasons surrounding the main reason - it’s a beverage they like to drink.

There are a few obvious ones:

They are enjoying it with others who prefer wine over other beverages, thus showing consideration for guests. I know people who do not really enjoy wine themselves and wouldn’t order it with a meal, except in the circumstance when those they are with enjoy wine. This is an inner reason, and a good one.

Somehow I sense you are looking for negative or cynical reasons. There are many, including the corollary to the reason given above, that their guests dislike wine and they want them to be uncomfortable. If this was someone’s reason for ordering wine, that would make them a jerk.

Some people buy wine for other auxiliary reasons:

To show off their wealth. I knew a guy who would have an old Lafite Rothschild with a cheeseburger. He did this to show off and become the center of attention. One could argue that a decent $20 bottle of wine would wash a cheeseburger down quite nicely, the $1000 bottle was a bit over the top putting it mildly. This made him a jerk.
Some people buy wine to show they are sophisticated. They often bungle the selection or otherwise display their ignorance about wine in the process, negating their intention to impress. This makes them insecure, immature, or possibly just a jerk.
Some people buy wine even though they don’t like it, because they want to be accepted and gain approval of those who do like wine. This makes them pathetic or at
least uncomfortable in their own skin as the saying goes. This is just sad.

I suppose there are an unlimited number of negative reasons why people buy wine. I have witnessed the ones above. But I must say they are rare, and I find most people buy wine because they and those they share it with enjoy it.

rượu vang cũng chính là hạnh phúc.