I grew up in Colorado and lived there my whole life up until around the same time CU bolted for the PAC-12. I can’t say I agree with this. The University of Colorado Boulder was always more culturally aligned with Cal and UW and Oregon than it was Oklahoma or Iowa State. It’s a research school with very high out-of-state enrollment (read: wealthy) and an outdoorsy active-lifestyle, extremely progressive campus community. Even 20-30 years ago, Coloradans felt kinship with other mountain states, not the Great Plains. John Denver made a whole career for himself by tapping into that sentiment. Obviously the move to the PAC-12 was a huge failure and money-loser for them but some of that had to do with the fact they hired a succession of truly abysmal coaches during their PAC-12 years. Just compare them with Utah, who came later with fewer resources and was vastly more sucessful. So yes I’m sure many at CU regret the move. But I think it’s revisionist to say their instincts were wrong when they moved west to a conference that was then bigger and better and more of a fit for the school overall.
The other thing is, the Big-12 they’re rejoining isn’t the same one they left. I don’t see who they’re going to be playing that is going to interest the fanbase. Nebraska (especially), Missouri, Texas, and Oklahoma are all gone. And I don’t think the Buffs faithful are going to consider a Saturday game against Cincinnati or Houston exactly must-see TV.