Passing-
There are a lot of assumptions in there at vastly skew your numbers. First off it looks like you are using the total population of Iowa, this would assume every man woman and child would make the $20 donation. This assumes a family of 5 donates $100, probably not realistic. A better figure would be using $20 per household which cuts your dollar figure down to about $15,000,000. Nice but again does not tell the whole story.
This would include non-sports fans, people that have moved to the state with other teams they support, people located along the borders that have loyalties to neighboring states/teams (NE, MO, IL, MN), and those that are on public assistance/fixed incomes. When you take those households out you probably cut that figure to below $10,000,000 (by a lot in my estimation). Granted you will get some alumni that are out of state but I don't know how much that moves the needle.
I think the more realistic way to look at it, and I think similar to the initial SWARM idea, is if each football game attendee incurred a charge of $10 or $20 per game. You would have to exclude student tickets, visitor tickets, and comps so say 60,000 per game which would be between $4M and $8M a season. Not bad but far from the rainmakers many schools have.