They are in the business of trying to balance the bets so that no matter which side wins they profit. This is why most bets you place you have to wager $110 to win $100. So if they get roughly equal amounts of bets on each side they win no matter what. And if too much money is pouring in on one side they move the line to get more action on the opposite side.
BYU consistently being underdogs in the betting markets simply means most of the people betting don't believe in us. The actual sportsbook is indifferent. It kind of makes sense if you think about it. Our fans are not likely to bet on the team, so naturally more people would be placing bets on the other side.