The NFL is not the hardest...
The oldest team that hasn't won a championship is the Minnesota Vikings, a mere 46 years old...and they've been in 4 SuperBowls.
The longest Championship drought is 59 years by the Cardinals...
There's only one team that has never made the playoffs(The Texans), and they're also the only team that's never made it past the first round.
And there are only 6 teams of 32 that have not played in the Superbowl...Cardinals, Saints, Browns, Jaguars, ans and Lions....and actually, the Browns have played int he Superbowl. as the Ravens...
3 of those teams...the Lions, Browns, and Cardinals...that everyone thinks of as the perennial losers of the NFL...have 10 NFL Championships between them..
Browns and Lions have 4 apiece and the Cardinals have two.
Football is not the most difficult...in fact after looking at it more closely...it's the easiest. It's an inevitability in the NFL.