act for one's own benefit(Accountability: An attorney is accountable to you and must act in your best interests. Joint account holders are not accountable to other joint account holders and may act for their own benefit. (rbcroyalbank.com)ART Vancouver)
pursue one's own ends(As a child, he had pursued his secret ways, indifferent to punishment or rebuke; as a man, he pursued his own ends, indifferent to jibes or persuasion. Alexander Demidov)