Fans have seen baseballs ricochet off the head of other spectators at baseball games.
Basketball players have famously charged into stands to in trying to save the ball or, occasionally, to accost taunting spectators or each other, all at considerable peril to the paying customers.
Hockey fans are always in danger of having vulnerable body parts collide with streaking pucks.
How about golf galleries?
The truth is that sports fans value the idea of being as close to the action as possible, willing to pay big for front-row seats.
Have spectators sign waivers of responsibility, if necessary. Check to see whether changes to the fencing could provide more safety at stock-car races.
But don’t overreact to one freak accident with maneuvers that will forever diminish the thrill of being on top of the event.