This is the default capitalist view. Anthropology disagrees. For much of human history we’ve exhibited altruistic behaviour towards one another. There are plenty of instances of that today: coalitions, unions, mutual aid groups, community volunteer groups… not to mention the individual choices people make in the interests of others over their own.
There is always some selfishness in people but it is a choice to structure society and economic activity around it.
Anthropology also shows widespread cannibalism.
I agree that many traditional cultures engage in egalitarianism, but genocide and mass-rapes, wars and slavery campaigns, are baked into the anthropological history.
Economic activity, expressed in water and caloric access, is the root of numerous ongoing conflicts (“tribal” and national), and the cause of many historical eradications of competition.
Capitalism seeks to maximize capital, anthropology says life just as brutal as it was before we named and systematized it. Cost benefit doesn’t need dollars as a unit of measure to be effective.
>Anthropology disagrees.
Survivorship Bias.
Humans that exhibit altruistic behavior get to stay around and make more history. When selfish behavior society collapses and that history is pruned, generally in some horrific event involving a lot of death and genocide.
Now, the mistake you are personally making is thinking you're going to make it because in general humans have stuck around after selfish people fucked everything up.
This comment is born out of a superficial understanding of anthropology, altruism and selfishness.
Most of the coalitions you mentioned are, ultimately, born out of the realization that, sometimes, you have to give a little now, to gain more later. Even charity at its pure idealistic form requires the altruistic individual to feel they made the world better in their own view (psychic profit, thus ultimately selfish) to happen.
This isn't the "default capitalist view", this is praxeology, plain and simple.