I don't think people are hopping on the bandwagon to be a "soccer fan", I think it's simply because it's an event that happens every 4 years and they are supporting their country.
It's the same as the Olympics, once every four years (actually every 2, but it's different because it's winter and summer Olympics). You think there are a ton of people who follow badminton, table tennis, fencing, and archery? No, but when the competitions are happening you support your country in those events.
by the way, I stopped reading the thread once it turned to shit, so sorry if somebody already mentioned this.