Honestly, I don't think there's any difference. All hobbies, interests and passions (if you will) require various levels of commitment, interest and money.
Monetary wise:
Want to watch that Soccer game exclusive to a channel? Pay the money for the channel.
Want to go to that Football game? Buy tickets.
Want to have the latest stamp from the USPS? Purchase it.
Want that comic book? Buy it.
Want that limited edition signed 'figurine'? Pay for it.
Chances are for all five of those examples, you're going to have some knowledge of them if one or more interests you.
Sports? You're going to know which team is the best, potentially which games they've lost/won. If you're buying that stamp, you're going to be buying it and have some knowledge as to how to preserve it. Getting that comic book means you probably know about the characters in it and what they've done in the past. Buying that figurine? I sure as hell hope you know about it, because they're expensive.
I literally had a friend with no interest or knowledge in comics tell me, after watching me talk to some fellow comic book friends: "You guys nerd out over comics like I nerd out over Fallout." His interest in Fallout is no different or special than my interest in comics, movies and .. other more girly things.
We're all 'fans' of something. If you want to go into the various degrees of how far into the fandom of your choice you are, go for it. But it means very little.
Negative reactions and influences can be found in any hobby or interest. Even if your passion is to just play POGS.
It's true. All athletes are human beings who live in reality and have to play by the same general rules everyone else does, except on a grander stage.
I think comic book characters actually reinforce a lot of very unrealistic character traits, like closely guarding a secret identity or just being a general anti-social prick (Batman, Wolverine). True, athletes can exude all sorts of negative traits but they'll face consequences for it. I think comics often placate anti social behavior, hence my remark that it's merely fantasy.
And video games encourage violence. That doesn't make them better or worse than Comic Book readers.