In class simulation

Yesterday we did a simulation in class. I was in group 4 and everyone decided to attack us at the end. I do not think they thought about what would happen if we got eliminated, another group would have to be eliminated after us. Today we all had a discussion about everyone wanting to attack us. Mainly everyone was just arguing and making good points to each other. My group and I made a secret treaty with group 3 but after they heard everyone wanted to attack us they started to back off from the treaty. People thought that their treaty with others would always stay there and they would not be broken but they could get broken. Mr. Stewart said we could lie and I am sure a lot of people would have broken their treaties with others just to save themselves. Why weren't they afraid of other groups? Who cares if we were being quiet whats the difference if we were being loud?