Ultimately it's the donor's motivation and decision-making, but a couple issues with the framing here:
(a) Illinois football was awful. Not just power conference awful, but would have been an average team (or worse) in many G6 conferences. For decades. It's tough to describe how many levels the football program has improved since Bielema took over. Two of the three best Illinois football seasons of the 21st century were the past two seasons.
(b) To argue it just needs to be the "next level" before the bigger donations start coming in sounds like a Nigerian prince e-mail scam. The chance of becoming an 11-win type of program when you aren't Texas, Georgia, Ohio State, etc. is insanely difficult and is likely an impossible target. Saying, "call us when you get there" while also ignoring the massive amount of capital that is a prerequisite to reach that threshold in the first place.
(c) Again, this ends up back where we started: The system is designed for donors having to keep up with 15% YOY increase in contributions just to keep pace with the others. If the donor's are lacking in motivation, or want to give more and have to choose between a much-improved football program or a F4 basketball program, or the program is hitting their capacity max, then you start to see the cracks. That's why I'm not blaming
@therealmiket86 for his take because it's likely true for some donors, but my argument is if folks saw Lovie win a total of 17 games, and Bielema took that program and won 19 games in just the past two years, and they still are not willing to give (or give more), then an extra win or two isn't changing their motivation.