I don't believe that is the case. According to this article Cory Hillard (Assistant AD) confirmed that CU makes an additional $1 million over what it could make playing the game in front of a sellout crowd in Boulder: http://www.coloradoan.com/article/2...-not-money-maker-once-Colorado-State-Colorado
That's almost equivalent to the value of the one-and-done CU did with Ohio State 2011 ($1.4 Million). I can understand why CU's administration has been unwilling to walk away from this series despite the protests from its fan base.
You may have been right in the early days of the series but I don't think that is the case now. The big payouts were a result of significantly larger crowds and even moreso a result of getting prime TV payouts, neither of those is the case now.
The biggest hinderance to ending the series is the same reason it started up again in the first place. CSU supporters in the statehouse applied large amounts of pressure to make it happen and a different generation of CSU supporters in the statehouse would be unhappy to see it end.
For a period of time it made sense for both schools to continue the series financially, now for CU I don't see that as the case. The crowd in Invesco isn't much bigger than what CU could get in Boulder for a regional opponent and CU would have access to the parking and concession revenues which isn't the case in Invesco. The game hasn't gotten a significant paying TV slot for a number of years so that isn't an issue.
CSU hates the idea because this game is still a big payday for them and the most significant game on the schedule for the huge majority of their fans (the numbers say the boot game isn't close.)