And I paid my ticket to watch a football game, not the back of someone's head. I am a short man. When everyone in front of me stands up, I've paid for tickets to be extremely acquainted with what the back of the guy in front of me's sweatshirt looks like.
Additionally, it's a chain reaction. If someone in row 3 stands the entire game, and that forces the people in row 4 behind them to stand for the entire game, row 5 has to follow suit or spend the whole game looking at someone's backside. Row 6, 7, 8, and so on and so on, have to follow suit. Then, that old couple or the guy who just had knee surgery, in row 25, is stuck looking at someone's back the whole game, having paid $25 to watch someone's sweatshirt.
But that's ok. You paid for your seat. You can do whatever you want, and the people who aren't standing are just fat lazy p.o.s.'s