What is it with men and foul balls? There's something about a baseball careening in their direction that causes them to throw out all sense of logic, not to mention human decency.
If anything else in the world is flying toward a man's head at a rapid speed, his first instinct is going to be avoidance. Whether he flees the scene or employs the duck-and-cover method, getting out of the way is a priority.
There will always be those who are able to pause and attempt to aid the women and children in their vicinity, but not everyone was built to play the hero. Although, in a foul-ball situation a hero isn't usually necessary.
That being said, there's a distinct difference between "not playing the hero" and actively endangering the welfare of oneself and others when the pressure's on.
In the event of a fire, would you run over a child or push a woman into the flames in an attempt to save yourself? Probably not. Even so, at least there would be something more valuable than a foul ball on the line.
Of course not all fans who REALLY wanted that foul ball are such egregious offenders—some just make asses of themselves! Here are some of the most ball-hungry fans in sports.