Because that’s what he would try to do. He cannot fathom that someone would voluntarily step aside and let a more qualified person take over. In his world there is only him. Everything he does is to benefit himself and himself only. He doesn’t believe in helping people. His father taught him that life is a zero sum game, and that helping people makes you weaker, since it makes them stronger, and there can only ever be one winner in any situation. So all of his actions are to hurt other people and help himself. He also can’t comprehend that people behave differently than he would, so if he would do something in a given scenario, he believes that’s what someone else must be doing. That is why every single one of his accusations is actually an admission.