Riots should be a sport themselves, no matter what you think of them they just always happen, there's always some that riot and some that walk away, oh and personal attacks to people on this forum are against rules you know, so I'd edit that out before a mod sees. Most riots are presumed to be a result as drunkeness but they just happen anyway.
The riotees on your side may not be people you know, once it's over you've mad a friend, so there is some benefit. Riots are cool but when it comes to people getting killed then it's stupid and over the top. Smashing windows and angry mobs is the cool and funny part. Without the riots then there's no action or anything to get heated up on after a match, happens all the time in the EPL.