There are 32 teams in the NFL, and since only 1 team can win a championship per season, each season approximately 97% of fans will be disappointed at the end of the year.
In a single decade, if there are no repeat champions (and every decade has featured multiple repeat champions so far), a minimum of approximately 69% of fans will not see their team win a championship. You can watch football for ten years, and there is over a 2/3 chance that your favorite team won't win a title in that time.
There are 16 NFL teams that have never won a Super Bowl in their current city. So if each of these teams takes turns winning the Super Bowl, and there are no repeats, and no teams that have previously won the Super Bowl win, you could wait 16 years before seeing your favorite team win. And there are always repeats, and there are the 16 teams that have won Super Bowls competing, too.
You have a 3% chance of seeing your favorite football team win a Super Bowl in the 2006 season. Yet you will probably watch every game, celebrating victories and mourning defeats, thinking about the team during the week, attaching all sorts of emotions to your team. And in the end, there's a 97% chance they will make you unhappy.
There are plenty of Viking fans around who have been watching the team fail to win a championship for its entire 45 year history. And there are many more that will devote much of their lives to the Vikings for the next 45 years regardless of whether or not the team wins a Super Bowl in that time.
Every sports fan must hate himself/herself to put up with this.
And yet...would you have it any other way?