Most, if not all, professional athletes and coaches are self-centered to a certain degree. Even the most selfless "team-first" types are still driven by a self-centered desire to squash the opposition and feed their own egos. It's not a bad thing, it's just the nature of competition.
A selfish need to win is what makes professional sports great—without it, we'd all just be like Bud Selig and settle for a tie. In fact, most of the greatest players and coaches in sports history are self-centered with a super-sized ego, which means a number of them are on this list.
The difference between most of the guys on this list and someone like Tom Brady is their friction with teammates and/or behavior off the field. You know Brady has a massive ego, but would he ever threaten someone for publishing a picture of him on a water slide? Or dancing like a goober at Carnival? No, because he has perspective.
Most of the guys on this list are great, but every single one of them lacks perspective. They can't quite balance being great and being likable—some can't even master being a decent human being. And before you dismiss this as "hating," just remember that I love more than half of these guys.