I am a sports fan, so take my opinion with the bias it deserves. I find that sports have a decent learning curve, understanding the rules of the game and how players and teams are doing things within those rules is fun and interesting to watch. Sports is also based on a foundation of vested interest. For me, my vested interest is watching teams whom I have grown up supporting, for others, it’s gambling and having a win case to cheer for.
If you don’t know much about the sport and have no reason to cheer for something, I can absolutely see why people would find sports boring.