Until ground staff clamp down on the number of carry on bags, these incidents will continue to occur.
A recent feeder flight from Humberside to Amsterdam, a family of people (4 adults, 1 child) carried on no less than 11 bags, and boarded first, due to the small (aged about 9). They then proceeded to fill ALL of the Euro Business class lockers (and then some) with their luggage an act of complete selfishness.
As I was sat in 1A, I moved on of their bags back, so that I could use the locker above my head, and mindfully dared them to challenge me about it. I would have escalated it with the cabin crew about the number of bags they had carried on, if they had said anything to me.