Egoism and Trust

Often conflated are Psychological Egoism and Moral Egoism--the former is the thesis that all behavior is, by nature, motivated by self-interest, while the latter is the doctrine that one ought to act in one's self-interest, which implicitly rejects Psychological Egoism.  Now, often unacknowledged by its advocates, each has its limitations--Psychological Egoism is vulnerable to being overridden by a Moral principle, e. g. Kant's, while Moral Egoism is relevant only to circumstances in which one is being repressed by an external force, i. e. it is not applicable where Psychological Egoism is in effect, nor where one is in voluntary relations with others.  Still, the two share one premise--that social interaction can be grounded on Self-Interest.  However, as has been previously suggested, the flaw in that supposition is that the positing of Egoism in others is the attribution to them of loyalty to only themselves, and, hence, of the ever-present possibility that they will betray one, in which case, one would be as foolish to engage with them as if they had already cheated one.  In other words, in both varieties, mistrust is inherent, and, so, neither can ground social interaction, e. g. notably, the process of forming a Hobbesian contract.