For many people, one’s personal interest is the primary drive to get things done, and that is nothing but a human nature. Or precisely, the part of it that is connected to animal instincts. We are rarely motivated to act out of sheer altruism even though philanthropic intentions are a virtue. But we put aims and achieve them if they coincide with our genuine interests. By the way, we are not always interested in materialistic things like storing wealth.
Acting out of one’s self-interest is referred to as egoism in philosophy. Altruism and egoism stand at the opposite ends of a spectrum of personality traits. But both of them seem to our personal well-being besides affecting other people. We shall assume, egoistic intentions appear due to one’s physiological instincts such as self-preservation, nutrition, or simply greed. Fulfilling our basic needs, all of us pursue own interests in the first place. Similarly, altruism is a revealing of compassion linked to our emotional needs. In a way, altruism also comes out of self-interest. Many people feel content if they do ethical things like volunteering or giving some aid. Such virtuous deeds make them feel good, which is also a personal interest.
Even if people do not act coming of their wants and needs, there is a balance of altruistic and egoistic deeds in their life. One cannot act exclusively for the benefit of the others because at some point it will threaten their existence. But in general, most of us preserve a good balance between deeds that can be called altruistic and egoistic.