AH!! Joe beat me to it, but this is what I was just about to post.

How many hundreds if not thousands of games like football, basketball, baseball, and for that matter, hockey occur every year WITHOUT there being any rioting? No, it's not SPORTS per se. Nor does it have anything to do with nationality.

It's down to sheer loutishness and nothing more.

Don Firth

P. S. And being male, I think I can fairly say that there is undoubtedly another ingredient in that mix of beer and adrenalin that burbles into a froth of hooliganism:   testosterone.

I've never heard of a riot breaking out after a Ladies' World Figure Skating Championship.