I'm going to push back slightly on part of this.
Robert Putnam, the "Bowling Alone" guy, has looked at why "social capital" has declined in the US (and other places, but let's leave that aside). He looked, iow, at why social clubs and overall in-person social contact has decreased. One of the major factors he found was - wait for it - TV. Before the explosion of TV as a source of entertainment, people had to go out of the house to get it. So they went to bowling alleys, clubs, local taverns, ect. in great numbers. Now we don't. We stay at home and either watch TV or, nowadays, call up HULU and watch movies, documentaries, game shows, and sporting events. Like college football. As in every game Tech plays. As little as 10 years ago this wasn't possible or profitable for college sports programs. Then overall attendance began to flag and the conference networks were started to provide the money.
I don't think interest in college football has declined so much. The necessity to attend games in person, however, has. Why show up if its hot or cold or raining or "it's hard to park" or <your favorite excuse here>; just watch the game on TV or your computer. This even applies for away games; they're all on TV too. Further, the saturation mentioned is also due to broadcasting all the games. For every team, almost. Combine this with a student body that has more diverse sports interests and you have the dilemma that is plaguing schools all over the country. Shoot, Bammer had to make attendance at football games mandatory for students not long ago. As for sidewalk fans … they can turn on a TV or computer too. Why spend the money and time?
Now, me, I like to go to college football games. I think the experience is a lot of fun, much more then watching the game at home. Even when Tech is having problems - like it is now - I usually go anyway. But that's because I'm socialized to do it. Younger people aren't and they really aren't interested in watching the team lose.
Btw, I don't think there's an easy way out of this. Or the donor question either.