and are investing in the highest NPV projects (in terms of furthering the mission of the church). To make this claim, you'd need to support the assumption that BYU football is a better investment than the other projects currently undertaken by the Church (including those projects that are put in place to ensure that the church will remain financially solvent into the future).
BYU football is entertainment that has positive externalities (e.g., missionary work). Because of this, I think it's on the fans to donate.