It can certainly be a test of mental acuity, and as such, one can benefit from physical fitness and a solid nutritional approach to one's diet. It does share this common attribute with sport, in that fatigue can definitely be a factor. That being said, it does not require much by the way of hand-eye coordination, muscle memory conditioning through training--unless you count chip shuffling--nor does it involve the testing your physical skills under pressure. So even while it is great competition, no, I do not consider it a sport.