These aren't fans. Fans actually like watching the games and following the team.
Merriam-Webster says a fan is "an enthusiastic devotee (as of a sport or a performing art) usually as a spectator." Synonyms are addict, aficionado (also afficionado), buff, bug, devotee, enthusiast, fanatic, fancier, fiend, fool, freak, habitué (also habitue), head, hound, junkie.
That doesn't describe these people. I don't know how to characterize them.