This is just another one of those attacks referred to as a “game” called Knockout King, where gangs of young black males pick a defenseless and often elderly or handicapped white, Asian or Hispanic victim at random and suddenly attack him (or her). I think the whole point is to show off to each other how brutal and pitiless they can be.
That’s considered a good thing in that “community.” One of the problems is that because it’s generally taboo to report these attacks honestly, there’s not a lot of public condemnation of it by more responsible blacks.