If a bunch of people become stranded on an island it doesn’t become lord of the flies turns out. Human nature is to help one another because what is good for the tribe is good for you.
We know this because it has happened, there are documentaries about it, and those are circumstances where there are actually limited resources. Currently there may as well be unlimited resources because there aren’t enough resources for one person to completely consume. I think it is perfectly unnatural the way the rich in particular act, and I believe it is under our current system in particular that drives people to act that way.