Well for starters i hate how people are presuming to know so much about this kid based on nothing more than about ten seconds worth of a low quality youtube clip. Yes, he could be an irritable little chav brat who fancied himself a free train ride. He could be like that because of dysfunctional parents or other factors outside of his control. He could also be somebody who'd run away from home and used all his money to get a train ticket, had a change of heart when he got there, tried to go back and now finds himself being attacked by a stranger and being trapped in a completely unknown place with nobody to turn to.
Yes, these are all somewhat unlikely extremes. But the point is that we just don't know.