Hate and mock some of their most cherished beliefs. It is part of their sports culture to be nasty and like it or not, this large number of fans embrace it. Not all are so vitriolic, I know that. However, those who don't act with such disgust don't want to be associated with these fans that are supporting the same team right next to them. Those respectful fans will never be able to shake what so many other fans represent. Again, because there aren't just a few punks.
They also can't hear that BYU is a superior academically. That BYU's athletic department as a whole, smokes their's. Rankings never matter.
They have a better football team for the last decade. Thumbs up.