Is that really Ben Stiller? Or Mark Hamill? Bluesky has more than 21 million members now—but it lacks a robust verification system. On Wednesday afternoon, billionaire activist investor Bill Ackman appeared to post on Bluesky a plan to destroy the burgeoning social media platform. Though the poster turned out to be an impostor, whoever it was so thoroughly captured the long-winded Ackman’s rhetorical style on X, they managed to briefly convince many people—including some high-profile journalists.