The point behind the question I posed was that the OP in this thread is making a fallacious argument because "everyone" is NOT into "only" IPAs. Even if you narrow it to just homebrewers and craft beer drinkers, you'll find very few people who "only" drink IPAs. You might find people whose favorite beer style is IPA or who like IPAs more than most beer styles, but you won't find people who are "only" into IPAs. In my personal case, my top three favorite beer styles in no specific order are: sour beers (in particular lambics and Flemish red ales), IPAs (especially West Coast IPAs), and dry lagers (in particular Japanese, German, and Czech styles).
So I corrected it to a more accurate (but still incorrect) argument. Lager is not only the most popular beer style in the US, it is also the most popular beer style in the world. While the "everyone" part obviously isn't true, there are tons of people who ONLY drink lagers.
And, in doing so, I was trying to point out the ridiculousness of the OP's question and also a point of "why do you care? It's none of your business." Just like there might be someone who eats nothing but hamburgers, but that person is not the norm, and it's none of your business why that person has decided to eat nothing but hamburgers.