You shouldn't really be a fan of the college football team of a school that you didn't attend
I’m sorry, but unless you're an alum, the only way you should be a die-hard fan of a specific school is if you went to a non-FBS school—or an FBS school with a historically terrible football team, like UConn or UMass—and you have family or loved ones who attend or attended that school, or you never went to college but have family or loved ones at that school. Too often, I see people attending schools with totally respectable football teams cheering for another university, sometimes even a rival of the school they're attending, which is just wild to me. For example, there are plenty of UCF and USF students who root for one of the Big 3 (UF, FSU, and Miami) over their own school. Even worse is when someone attends one of the Big 3 but cheers for someone else, like a UF student rooting for UGA or FSU.
If a school rejected you, you definitely shouldn’t be rooting for them. That’s a given. But often, these students were accepted but chose not to attend due to costs, saying, "UCF was a lot cheaper for me than UF, but I’ve been a Gator all my life." Well, that’s exactly why you should be rooting for UCF first and foremost. Cheering like crazy for a school you don’t even attend is just bizarre. At the end of the day, UCF is the one giving you an education and making it more affordable, not UF.
Aside from my own anecdotal experience, I see way too many influencer accounts on social media that aren't even students/alums of the schools they're super fans of online. I am just a firm believer that the beauty of college football lies in its pure form of sports tribalism. There's something special about earning the right to root for a team. You work hard throughout your youth, get into a particular school, and sometimes even pay more than you might elsewhere, all to earn the privilege to call yourself a Gator, a Bulldog, or a Buckeye. Then, you carry that pride and connection for the rest of your life, as attending that school becomes a defining part of your journey. Ultimately, outside of some very unique circumstances, I think most of these other fans that didn't attend these schools are no different than bandwagons, if not worse.
Edit:
If you went to like a small school that is part of the same university system (ex. UT Chattanooga, UT Dallas, UW Milwaukee, etc.) and these schools don't have a renowned football program (they usually don't), then it's fair game to root for the flagship school.