I think it is the sign of the times. For the cost of 2 season tix, you can really make a nice man cave, with 55 in tv (at least), air conditioning, enough toilets for everyone, better food, and a hell of a party, etc. And over the last 10 yrs or so, gas has skyrocketed (yes, I know it's currently the best it's been in a long time) as well as hotel's are gouging. (which, hotels have always gouged)
Then the complete aggravation of parking and tailgating. Used to be able to park anywhere. Friends could all be together in "their spot". Would even camp on Friday nights to secure that "spot". Adams and Damon changed all that. Broke up a lot of people's traditions which has made the bigger tvs, parties at home, etc. much more attractive.
But you never want to give up your season tix entirely because then you start over. That piece of real estate in Sanford you think you own because you've been in the same spot for years and years, you lose. So you sell the games you don't want, stay home in the cave and come to the ones you want to come to.
Just my 2 cents.