There's a certain level of competitiveness that is healthy and beneficial to all of society as well as the individual.
And then there's a level of competitiveness that crosses the line and is unhealthy and just sad. A grown adult having a tantrum after losing a game of billiards. There's something that is so insecure about Brady, being in a constant mode of "prove them wrong" and "I'm better than you." He'll never be satisfied, or at peace. Segments of our society celebrate this type of animalistic behavior, which is unfortunate.
'Pathetic' might be a little too harsh and insensitive. But not completely inappropriate.