You think there's 50K in the seats for more than 1-2 games a year? We couldn't sell out a 35K stadium consistently. It is what it is and it's always going to be this way. It's a private school with a small undergrad enrollment, the majority of which come from out of state and have very little interest in being bussed to a stadium 30 mins away to attend a football game. If we could build a stadium on campus, which obviously has a literal 0% chance of happening, then maybe more of the kids would just walk over and go. But it's still a very small number. However, that's not a possibility, so we'll continue to do what we've been doing. The school is very happy with the partnership/lease with HRS. They have no desire to break it, even if they could, which they can't.
Win some football games. That's the answer. Don't go 0 for eternity in the redzone against A&M, actually beat MTSU, and you'd have had 60K in there for UNC. When the team loses, people find something better to do with their time. In many, many other college cities around the country, that's not much of an option.