But one can work without any self-interest for the betterment of the world. There is no personal give-and-take; it is impersonal service. But there is one point to be noticed and that is a man renders service for the most part to satisfy his ego. Ego-satisfaction is the urge behind the service.
This betterment of the world takes for granted so many things. One of them is that the betterment is according to one's own ideas. Thus, it is subjective and the man feels that there are certain flaws or defects in the world created by God and that he is doing the work to set it in order. One's own ideas are reflected in the service and the ego is nourished. Of course, the service rendered is of a higher order and is not of the same crude form as in the previous one.
There is a small story which illustrates the point. A thought came in the mind of a wise man while walking on the road. He saw a very big pumpkin on a very thin creeper. He felt what is this arrangement of God where how a creeper can carry the weight of such a big pumpkin. As he walked further, he saw a very tall, strong tree of gooseberry (Amala) and very tiny fruits in a very big number on each of the branch. He almost concluded for certainty that there are certain flaws and defects in the world created by God. And as he stepped further, a small amala dropped on his head and then, understood the way of working of the God!
It is something of this type that happens to us and we feel we know everything and become egoistic. Care need to be taken, isn't it?