You don't like it. Countless others do.

Marketing is more the case with sugared water (ie.e. sodas, that actually spends billions in advertising each year), than with champagne, which is not a single-brand product but tons of different producers, and that was popular way before modern mass marketing was a thing.

People seldom get to even see champagne commercials except in posh magazines or during the holidays. Contrast with sodas, beer, and co.

No marketing needs to be involved, except to promote this or that particular brand of champagne, and that only in the last century.

There's a lot of different wines that go under the champagne moniker because that denominates the origin region.

Sugar content vary wildly between labels and with that the taste. A lot of people whom don't like wine do like champagne because of the sugar overwhelming much of the other acid tones, and call it "fruity".

Also tannis contents vary a lot between bottles which can cause varying reaction to taste and enjoyment, up and including migraine.

With all that I mean there's a chance that a champagne/wine of your liking is out there but it's hard to find because labels prefer to talk about flavors and notes instead of giving out useful information

I don’t know. It’s not really a fad.

I love it. Champagne pairs well with shell fish and in particular with raw oysters. However, bad champagne (bubbly in general) or flat champagne is not very enjoyable. You don’t need to spend a lot but cheap stuff that’s too sweet (and isn’t Demi Sec) is pretty awful. There’s a true craft to making good bubbles.

I used to love the stuff, now it gives me terrible acid indigestion and I don't care for the taste anymore either.

Each to their own I guess, but I agree that "universal appeal" is overblown.