I've tried to make some searches on egocentrism and its opposite (Allocentrism).
The definitions from Wikipedia are:
Egocentrism is the inability to differentiate between self and other. More specifically, it is the inability to untangle subjective schemas from objective reality; an inability to understand or assume any perspective other than their own.
Although egocentrism and narcissism appear similar, they are not the same. A person who is egocentric believes they are the center of attention, like a narcissist, but does not receive gratification by one's own admiration. An egotist is a person whose ego is greatly influenced by the approval of others while a narcissist is not.
Allocentrism is a collectivistic personality attribute whereby people center their attention and actions on other people rather than themselves.
But since the prosocial actions are often motivated by ego needs (see Polatch effect for the extreme) can we say that among extreme idealistic people (i.e. militants in extreme organizations) we can find Narcissists as well?
A narcissist has absence of self-compassion, he thinks to be perfect. Is there a correlation between some form of Narcissism and altruism?
EDIT: I found this
“(The) Israeli zoologist Amotz Zahavi (suggested that) (a)ltruistic giving may be an advertisement of dominance and superiority. Anthropologists know it as the Potlach Effect ... Only a genuinely superior individual can afford to advertise the fact by means of a costly gift ... through costly demonstrations of superiority, including ostentatious generosity and public spirited risk taking... (I)f Zahavi is right ... conspicuous generosity (is) a way of buying unfakeably authentic (self-)advertising.”
(any help at improving the question is very welcome)