Although Macbeth’s downfall was caused by many things, the most prominent was his pride and strife for it. He had many things to be proud of in the beginning of the play but by the end he had nothing, not even his own life. He was already the Thane of Glamis and he just got promoted to the Thane of Cawdor. Two of the four prophecies from the witches have come true. Macbeth should be proud of what he has accomplished, but he’s not, he can't get his mind off of, “All hail, Macbeth, that shalt be King hereafter!” (I.III). The witches have already proven their legitimacy by predicting correctly the promotion of Macbeth, so Macbeth can’t let go of the probability of becoming king. If the first two prophecies had come true, and he was now the Thane of Glamis and the Thane of Cawdor, who’s to say he won’t become king like the witches said? Macbeth believed with everything that he was that he was meant to be king, so he thought if it's going to happen anyway (like the witches prophesized) why should he have to wait for it to happen if he could make it happen right now, “If chance will have me king, why, chance may crown me, Without my stir.” (I.III). His wife, Lady Macbeth, was saying that he wasn't a man unless he killed Duncan on his own , “When you durst do it, then you were a man” (I.VII). I'm not a man but if I was I'd definitely want my own wife to think I was manly, that's definitely prideful. After Macbeth does kill Duncan and become king, instead of being proud because he did what he's always wanted to do and his wife is now happy and thinks he is a manly man, he starts worrying about other people trying to take what he has away from him, the kingdom. Especially because of the witches final prophecy (that Banquo will be the father to many kings). Macbeth now worries again about anyone trying to take what he's “proud of” away. That's why he kills everyone else that he does. He is afraid of his kingdom being pointless, how could someone be proud of a pointless kingdom, “No son of mine succeeding. If ’t be so, For Banquo’s issue have I filed my mind; For them the gracious Duncan have I murdered” (III.I). He doesn't want everything he's done to be for nothing in the end, he's striving for pride in the long run, and that's why he kills, and that's why he eventually falls.