It seems to me that selfishness/self-interests is a biologically inbuilt part of human nature. Fundamentally, we all want more; we all feel that our lives would be better "if only" we could have more of something or other.
I disagree very strongly with that statement.
Anthropology, and history, and even a cursory examination of the psychology of many individuals in our own society, show that such is not always, or even usually, the case in human societies.
Modern Westerners, and especially brainwashed American consumers, often fall for the line that is constantly being pushed at them, that their lives will only be complete if they have more of this, that, and the other thing.
That just shows where they are from!
It is intellectual slovenliness to assume that what is true of us, or the people around us, is true of all people and all situations.