Both Bryson and Koepka have douchey qualities. From the beginning of that interview Koepka exuded 'tude. That said, Bryson seems douchier.
There are always exceptions, but individual sports like golf and tennis often breed self-entitled attitudes as you don't have teammates (or even opposing fans) to give you reality checks. Also, in individuals sports, the coaches work for the player. The player hires, fires and pays the coach. Given that dynamic, coaches essentially have to pander to the players (that happens with total superstars in team sports, but not to the same degree).