I think the main difference with sports is that with sports, you need good healthy rivalry between certain teams to make it a lot more fun.
Over here there is Celtic and Rangers, but that is a very unhealthy rivalry, as the basis of it is in the Catholic/Prodestant(sic, i am Catholic) divide.
Up until about twenty years ago Rangers *never* signed any player that was Catholic as a point of policy, that is how bad it was.
But, if you have teams that have an inbuilt rivalry, it makes the games far more exciting and the rush of the win is not comparable to that of beating any other team.
I am not into watching sports these days, but when I was growing up everyone around me was into football, so i ended up watching(and playing)a lot of football games. So I ended up going to quite a lot of Celtic games in my childhood. When I started watching a game, i would get into it, and it is fun being at a big sports game, so i recall what that feeling is like. But, do I switch on the tv now to watch games, no, lol. edit: and after reading E-Man's post after mine, maybe that is just because of that particular sport, I mean, i have read jokes that Americans make about 'soccer', as in, you can sit for ages bored out of your skull cause there is no scoring going on, and it is true, some games are great to watch, but they can easily get boring when the players are playing it safe. So maybe I would be a fan of indoor synchronised swimming, bowling, American Football, baseball, hockey, basketball, who knows, i have never watched them. Although i did used to really enjoy playing World Series baseball on my old Spectrum.
With comic books you don't need that kind of rivalry at all, i never understood any kind of DC fans/Marvel fans divide, to me a cb/sh is a cb/sh, I don't care who publishes it, I'm only interested in the character.
I guess a similarity is that writers and artists change on the books, and even if they go through changes the fans don't like, a lot of them will stay loyal to the character. Same as with sports teams, when they go through management and player changes the fans don't always like, they will stick with the team they grew up with(or however they got into the team). I think that is how most people get into teams right? Your family was already into that team, so you grow into it, or they are the most local team, or sometimes a religion thing is interconnected to the team.