I remain convinced she is asexual / has never f*cked and the boyfriend press/song cycles are there to convince you otherwise. But then again I also thought the Bey/Jay drama was mostly made up to sell records.
I can't explain it completely, but I can say she gives way more convoluted and involved biographical information in her songs than most musicians and encourages her followers to be parasocial, and seemingly this interest in The Lore has lead her more obsessive fans to spread interpretations of her songs that are absolutely ridiculous.
Also there are plenty of actually gay musicians please show them some support instead of making fanfiction up about the billionaire that flies her private jet more than anyone else in the world.
Its people who want the clout from supporting a gay artist but they dont want to do the difficult and scary thing of listening to something new for the first time, so you just headcanon the pop star who has been mega famous since you were a kid into the gay icon you imagine you would listen to. Also: Harry Styles.
Is it an actual cult or is it just people acting as if obsessed teenage fangirls being weird and attached has never existed before? They will grow out of it in 5-10 years.
It's not teenage girls though. The most obsessed swifties are usually in the 20-30 range, people who literally grew up with her and her apparent lifestyle and music changes. Teenage girls do listen to Taylor Swift, but your average teenage girl is just as likely to be into Billie Eilish or Ariana Grande or any K-pop. The people who get para-social with it (to name a couple of real-ass examples, getting tattoos of her handwriting or theming rooms around different albums) are the people who have been celebrity gossip column following her for years, and trying to convince their friends that in fact she personally writes all of her tweets well into their 20's.
Her music is whatever, what bothers me is how deeply they've fallen for the marketing schtick.
Edit: More specifically, it is their tendency to think that if you don't fall for the marketing schtick, that makes you a 'bad person who is just jealous of her success'.
I think for a few celebrities- Beyonce, Nicki Minaj, Taylor Swift, Elon Musk, Jordan Peterson- there's a point where it becomes a whole new level of parasocial relationship. The line between toxic fandom and cult is pretty blurry. The hosting website also has a bunch of hentai and shit so NSFW but that episode of QAA has some pretty extreme fans using biblical gematria to prove that Taylor Swift is secretly gay: https://kemono.su/patreon/user/12883973/post/93239821