Imam sheds light on the matter in his famous book of "an expositon on Forty Hadith as following:
If we think about it, and examine the plight of such people, we shall notice that every one of them, despite the enormous strength they possess, and most of their wishes being fulfilled, they still nurture thousands of new desires that are yet to be fulfilled.
It is not possible in this world that all the desires and ambitions that we cherish be fulfilled here, since this world is the abode of obstacles.
The elements of this world dispirit our wishes.
Our desires are also not limited.
For instance, the power of sensuality and lust acts in man in such a way that if he is given one woman, he is attracted to other women.
If he is given an empire, he will hanker after some other empire.
Man always desires for what he does not possess. In spite of this vanity of imagination and futility of human desire, the kiln of sensuality is always hot, and its heat ever increasing, and our desires are never cooled down.