It's a combination of winning and culture. Part of being motivated is a chance of seeing a winning team, but McC's teams win as much or more than places that have packed houses.
A lot of it is the culture. The culture died with the ass wipe Alford and Lickliter created a clown show. Alford was very off putting, and I literally don't know anyone in Iowa that likes him. Particularly in the early years where he made it pretty clear he was waiting for the Indiana job while his later years featured good players that collapsed against weak opponents. He brought in some dislikable players that were even more off putting. He was on a win or go demand when he beat the hangman out of town. Then Lickliter made it even more ridiculous, producing the two worst teams in Iowa history.
Then the always crazy Iowa BBall fans were/are still locked in the 80s and the expectations were completely unrealistic. So, the fans started to disappear. McC is seen as a failure because he hasn't restored pre- Alford/Lickliter Iowa. With the arrival of NIL, portal we may never reach the status of the 80s.
Alford was supposed to take Iowa to a new level than Davis-and he sure did. Quite the new level, all the way back to the 70s years between Ralph and Lute. Then Lickliter was sold as the anti-Alford who would bring stability and regular success. That was a little wide of the mark. Both were hot coaching commodities when hired. So, it became uncool to actually attend the MBB games.
Having an arena that is no longer well suited to purpose and requires a lot of walking and has poor parking facilities and terrible amenities. The ice cream is so not 2024.