It’s not the first time that a row about something fairly minor has flared up into violence. The singer was being selfish, and refusing to allow somebody else a go. That does /not/ of course justify killing him.
The problem, as I see it, was that somebody was carrying a knife, and in the heat of the moment, decided to use it. So what would otherwise have been a brawl, turned into a murder.
There seems to be a ‘knife culture’ which is sweeping the world. I for one am beginning to feel unsafe walking down the road, in case some nut decides he doesn’t like me for some reason and stabs me.