Many of the Swifties are not independent women, but dependent on their parents for support, shelter, and to pay for concert tickets and transportation. Folks in Red states, especially now, will think twice before shelling out $1000 for tickets for their daugther(s) to go to a show where the headline act will ask them to vote against their interests.
She may alienate half her audience, but a good part of that "half" is footing the bill for her concerts and merchandise. Sure, some will vote for JRB, some will not, and some the sweet, impressionable young women with working-class parents that she counts as fans will stay home.
She's already taking a risk by being so gushingly public about her romance with Kelce; the smartest thing she could do is quit while she's ahead and sit this one out.
Conservatives don’t listen to Taylor, anyway.