No, I've had that path before me once before and I failed at stepping on someone to get further ahead. I think if I had, I would still feel bad today. Sometimes I wonder what would have happened if I did, but still know that it wouldn't have been worth it.
That being said, everyone is always doing that to some degree. If you have something, that's something that someone else doesn't have. When I take a job, I am leaving countless other people - for the moment - jobless. But there has to be a line between taking care of yourself and kicking other people out of the way.