Irrationalization and Selfishness

I am going through Bertrand Russell's Sceptical Essays and found a successful strategy called 'irrationalization' where,

Having come to a sound egoistic decision by the help of the unconscious, a man proceeds to invent, or adopt from others, a set of high-sounding phrases showing how he is pursuing the public good at immense personal sacrifice…In this case a man appears less rational than he is; what is still more curious, the irrational part of him is conscious and the rational part unconscious.

I don't know how to feel about this. It assumes a couple of things:

1. The unconscious mind¹ knows or can know the really beneficial actions, and
2. the veil of sacrifice helps in the person's goal

The high-sounding phrasing definitely can help in setting up a favorable environment for the unconscious plan, but I still don't feel very comfortable as to where this comes from. Something similar connecting public good and selfishness pops up in a later page:

…when people are mistaken as to what is to their own interest, the course that they believe to be wise is more harmful to others than the course that really is wise.

Again in a later essay:

In an ordered community it is very rarely to a man's interest to do anything which is very harmful to others

These point to an assumption that real personal selfishness is not in conflict with societal harmony (a little selfish gene vibe), most of the time. I haven't seen this logically concluded outside the biological study of altruism. It will be interesting to know the philosophical roots of this.