It's why I have "Nobody in particular" listed under who I support. Got older, life got more important things to care about than cheering on some sports team, and where I was frequently in the stadium in my youth I now sometimes don't even watch games when I have time, but am just not feeling like it at the moment. It's just a game at the end of the day, it's not who I am. Still love the sport and watch a fair share of matches, still got teams I favour or dislike, but it's not a focal point of my being.
I also think it's just way easier to get saturated with the jam-packed calender of games these days. It's easier to look forward to games if they are a treat here and there, but if there's always a game on a stream somewhere and your team plays every week, sometimes twice per, the individual matches just feel less important and special.