I think you'd be surprised just how popular it is outside the US. I really struggle find any sort of sense to it. You get British people, for example, who probably haven't paid any attention to American Football since the last Super Bowl, arguing about which team is better and who they support. Now, unless it's a phenomena I just can't understand, they must just want to dive into the hype and everyone is faking the enthusiasm to get in with the big-event-vibe.
Even here in Iceland it is receiving a lot of attention, whether for the amount of adverts for it, where it's possible to watch it on Sunday, recaps of the last season. There's a notable upsurge in the term Ofurskálin ("Super Bowl"). But they also have an obsession with English football that I wouldn't have expected from a country outside of the UK.
This obsession that takes over people (outside the US) for this event has boggled me for the last few years.