In Night, we see how many different people have become greedy in the war. Franek sees Elie's gold crown and demands Elie give it to him. Elie comes up with a couple of reasons as to why he can't give it to him, and finally tells him he needs to get his father's advice. Franek agrees but Elie knows that he will make his life hell until he gives in to him.
Unfortunately, Franek knew how to handle this; he knew my weak spot. My father had never served in the military and could not march in step. But here, whenever we moved from one place to another, it was in step. That presented Franek with the opportunity to torment him and on a daily basis, to thrash him savagely. Left, right: he punched him. Left, right: he slapped him.
Elie could not sit back and watch his father being treated this way, so he eventually gives in to Franek and gives him his crown. Although Elie has hard feelings towards his father, he still loves him deeply and wants to make sure he is okay, no matter the cost to himself.