If Not a Sport, then What?

Dennis Monokroussos argues against chess as sport:

It might at first seem that chess is a sport. First of all, it's clearly a competitive activity, which seems to be a necessary if not sufficient condition for something's being a sport. Second, the same sorts of general mental and physical disciplines needed by the sportsman (e.g. mental toughness, strong self-confidence, endurance, etc.) are required for chess players to succeed. To take a prominent example, Karpov's (then-) frail physique nearly cost him twice in big matches against Korchnoi (one for the world championship, the other in a final candidates match) and quite possibly did cost him the title to Kasparov when he lacked the endurance to finish him off in 1984.

Yet despite the above, I think that chess is not a sport.