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'.