Some of Taylor Swift's fans want you to know three things: They're not still 16, they have careers and resources and, right now, they're angry. That's a powerful political motivator, researchers say.

Look what Ticketmaster made them do.

It started Nov. 15, when millions crowded a presale for Swift's long-awaited Eras Tour, resulting in crashes, prolonged waits and frantic purchases. By Thursday, Ticketmaster had canceled the general sale, citing insufficient remaining tickets and inciting a firestorm of outrage from fans. Swift herself said the ordeal "really pisses me off."

Ticketmaster apolo...