I'll be the first to admit that CU games are expensive. It's an expensive hobby. When you add the donation, ticket cost, parking, and all the beer, food, etc for the tailgates, it adds up. Having said that, it's still less expensive than going to Bronco games or having season tickets to the Rockies, Nuggets or Avs.
If the Broncos were a total dog **** team it would be a different story. By dog ****, I mean like Detroit Lions or Phoenix Cardinals kind of bad. So bad that there's virtually no chance that they'd ever win anything - ever. In a situation like that, the Buffs and Rams would have better following. Football is a fun game to watch. The game sells itself in many ways. But that's not the situation. The Broncos are a good team and they probably will be for a long time. The result is that both CU and CSU have to do everything they can to generate fan loyalty and passion.