Some folks will win big on a one point Superbowl
Seattle opened as a two point favorite. This was one of those cases where the NFL bet taking establishment mis-guessed where the betting sentiment would be because almost all bets were on Denver (plus 2). So the line moved very fast to the oppositeDenver favored by 2 points. (And now Denver favored by 2.5 points.)
Many big sports bettors would have jumped on Denver +2 when betting opened and be holding those tickets. And some of the same folks will now place similar bets on Seattle +2.5 because they grew up on the stories about folks who bet on both teams and won in the late 1970s Cowboys-Rams (I think that's right) super bowl where the line moved a lot.
Anyway... if Denver wins by one point or Seattle wins by one or two points (all reasonable outcomes and probably roughly as likely as any other set of three outcomes) there will be a meaningful number of folks getting paid off on both teams. Which happens from time to time, but is an oddity.
(I don't bet on football, but I find the topic of betting somewhat interesting.)