The root-cause of suffering
As mentioned earlier, lacking a permanent Ego at the center of our being and transitory in our nature, we long to find and to cling to something substantial in the ceaseless flow of change. We therefore project reality onto an illusory Ego for the purpose of gratification. Possession is used as a means of ego-gratification to fill this void. The use of people as objects to be manipulated for our needs is another way in which we attempt to solidify ourselves. But it is like building a house on sand. There is nothing substantial there. The grains fall apart and dissolve, and the house crumbles into dust. We still feel inadequate or unsatisfied, no matter what we get, because our ego-desires (tanha) are by nature insatiable.
It is seen in Buddhism that much of the misery of life is caused by self-centeredness and the constant desire to satisfy one's own needs. These ego-desires are the very root of all evil, including greed, lust, hatred, lying, deceit, and crime. It is the delusion of the Ego that begets all forms of these ego-desires. Because ego-desires are the cause of most human suffering, it is the elimination of the Ego that is necessary to end our unhappiness. And because the Ego has no reality of its own we are able to abolish it through our efforts. This is not seen as an easy process.
Buddhism discourages ego-focus because it wants us to realize our nonpersonal potentialities. Besides, self-concentration does not allow the pursuit of truth and righteousness. The value of life does not depend on quantity but on quality. Any life lived solely for the self is a life not worth living, as there is no room for the highest goal of attaining nibbana, the liberation from the endless life-cycle, samsara existence. It is this ultimate goal that makes life worth living. Thus to be absorbed and engrossed in the temporal, impermanent part of life matters little.