CNN  —  Billionaire Bill Ackman and organizers of a tennis tournament have been strongly criticized by former grand slam champions and social media after the hedge fund manager made his professional tennis debut, a match he ended up losing. Ackman, who has a prominent social media presence on X, played with three-time grand slam doubles champion Jack Sock in the men’s doubles at the Hall of Fame Open – an event sanctioned by tennis’ world governing bodies, the ATP and the WTA – on Wednesday