I Don't Get It

Why do some veterans deny that the Atrocities commited by other veterans did not occur? Why would anyone brag about something they are not proud of? I am sure more than 50% of the soldiers in Iraq did not witness what was going on at Abu-Grahib prison. I am also sure that the majority of soldiers have not disobeyed direct orders like those in the supply brigade. Why are these called isolated incodents? Do we call them "isolated" so that we can say later that they did not happen? The veterans that spoke out, and admitted what "they" had done, spoke only for themselves and the experiences which "they" had, and not what "other" veterans had. From what I have seen based on John Kerry's testimony, he spoke of what occurred based on the stories and recolections told to him by fellow members. Kerry was their represenative. Kerry does admit himself to witnessing and commiting some of these autrocities. What is not to believe?