I can understand that he is nervous and that has turned into a selfish individual who only cares about himself.

individual 是名词，指"个人、个体"，强调与群体相对的单独个体。这个词来自拉丁语 individuus（不可分割的），由 in-（不）和 dividuus（可分割的）组成，原意是指"不可分割的最小单位"。在这里指代"这个人"的具体存在状态。