Yeah, I know, the headline above is too easy. What do high school players not know? Try everything. The point, though, is an article discussing a study of high school football players and what they know, or don't know, about concussions. Many players, it says, "are not concerned about the long-term effects of concussions. The study also states that these athletes fail to report their own concussion symptoms because they are afraid to be excluded from play."
In other words, not only do they not know much, they don't care about what they don't know. Why? Because. They. Play. Football.
And, as my dad used to say, they're "young and dumb."
That about sums it up.