College football is bigtime. They sell out stadiums that sit over 100,000 people. It's a different animal where it's more about recruiting than dealing with salaried players. Jim Harbaugh left the NFL to go back to his alma matter. It's just what environment you want to be in and the control you can have.
not many successful HCs opting out of the NFL to go back to college...
a lot of the nfl guys who go back often couldnt or didnt hack it in the NFL or they were lower down coaches who got a significant promotion in the college game
because the quality of the players and the games mostly sucks - 2020 was one of the most interesting college seasons for me mostly because the SEC played itself every week and suddenly there was some decent competition at times...
yes the fanbases in some of these places are huge and the stadiums but my god is the football often boring - like i watch it mostly on my saturday afternoon/evening when there's nothing else to watch but mostly i dont start watching until bowl season and even then it'd better be good teams playing and even then it's mostly because im watching draft prospects