... I'm not against storming the court (or field) after a signature win but you have to realize 1000+ people surrounding the opposing teams is a recipe for something happening.
Even without storming the field, I find the ending of games, concerts etc to be a little sketchy.
When I go to an event all the staff are on the ball at the start.
Security is being alert and careful, ushers are doing their thing, fans are focused on settling-in.
At the end of events everything is breaking down.
Security starts going slack and making personal phone calls.
Fans are leaving garbage all over and some are tipsy.
Fans and staff cross a line in their minds when events are over
Even at military sites things start to go slack.
Someone malevolent trying to sneak into a site can have an easier time when people are leaving and staff are looking lax (maybe looking for concession leftovers etc.)