She’s a “self-made” female billionaire. Her money isn’t from something like Walmart or Amazon, where it’s obvious how she’s exploiting people. It’s clear she’s very talented. And she seems smart and like she won’t get pushed around by scummy music execs (Taylor’s version).
Her music speaks to people and makes them feel like they’re understood and like they understand her. When she got a lot of hate (because most things teenage girls enjoy get a lot of hate), plenty of people felt personally attacked, and that made them more defensive and appreciative of her. She poked fun at the stereotypes making her more endearing.
That’s why self-made is in quotes. But many female billionaires are primarily heiresses little known or primarily known as a male billionaire’s daughter/wife/ex-wife. Swift turning millions into billions is about as self-made as any other billionaire.