You do realize that its not the fans that play the game. The fans can get as excited and cocky as they want, its the players that can't get overconfident.
Senator can justifiably continue his 19-0 mantra and he has every right to. This is what the fans need, it gets them excited possibly buying more tickets and merchandise. Let the fans gloat and cheer all they want, it will not effect the outcome of any game in the future because the fans were overconfident.
And its the job of the coaching staff to make sure the players don't act like that.
Hell the Bills crushed someone on opening day on the road, enjoy it, have fun with it. Yell at the top of your lungs the Bills are going to the Superbowl, we as fans need this. If we lose the next fifteen, so be it. We still got to enjoy a great win for 1 week.