If this documentary changed your life, you might like this video: https://www.youtube.com/watch?v=LY0_5Sk5GYs
Are you saying that because cruel things happen in the wild we should be fine doing cruel things? I doubt we would accept someone justifying other acts by showing how it occurs in the wild such as stealing all the way to something extreme like cannibalism.
What animals do in the wild is vastly different from what we do to animals.