You do not have to wait for food to run out. There is always 'that one guy trying to ice skate uphill'. They test the limits on everything and do not care about others at all. It only takes one jerk to ruin a party. I know at least 4 people like this, probably more (they hide it better). They would rob you in a heartbeat if they could get away with it and even if they cant. But in general they seem nice and happy and stable. The reality is they just do not want to get caught.