We tend to blame others for their misfortune because we try to distance ourselves from thoughts that we might experience the same misfortune. We are driven by our emotional and motivational drives that's why we have attributions. When something went wrong to others, we are triggered to explain why it happened to them. Thus, it results to blaming the victim instead of looking at the context or system.
When we are the one that is responsible with a certain problem, we are triggered to defend ourselves. We are all afraid of failures, so we make attributions explaining why it happened. We blame and judge others to avoid or deny our responsibility to the problem.