On the one hand, he was an absolutely cruel person. First, in order to ascend the throne as soon as possible, he killed King Duncan who gave him his honour and wealth. After the king was killed, Banquo, suspected Macbeth got his own crown by a devious way. Additionally, Banquo told Macbeth that: .
I fear, .
Thou play'dst most foully for't; yet it was said.
it should not stand in thy posterity, .
But that myself should be the root and father .
of many kings, (Act 3, Scene 1, Lines 2-6).
Due to this conversation, Macbeth was worried that Banquo would tell the truth to his lords. Moreover, in order to eliminate the possibility of Banquo's son ascending the throne in the future, Macbeth employed three murderers to kill Banquo and his son, (Act 3, Scene 1, Lines 46-71). On the other hand, Macbeth still had some conscience. After he killed King Duncan, he was feeling so sorry about that, he said: "This is a sorry sight, (Act 2, Scene 2, Line 21)." to his wife. And the guilt made him unable to sleep anymore, (Act 2, Scene 2, Line 41-43). After he indirectly killed Duncan, the fear and guilty made him have hallucinations. Finally, huge pressures made Macbeth go crazy in front of all his lords, (Act 3, Scene 4, Lines 75-83). After Macbeth went crazy, gradually, the lords thought "Things have been strangely borne, (Act 3, Scene 6, Line 3)." Some of them don't want to believe and stay with Macbeth anymore, so they fled to England to help king Duncan's son, Malcolm, to overthrow Macbeth. In my opinion, Macbeth's humanness is the key to his downfall. He had ambition and the courage to be king, but after he became king, his conscience wouldn't let him forget what he did; his guilt make him doomed to fail.
When a fortune-teller tell us we will have a good fortune, will you just sit in your house and waiting for your goodness without do any effort? Of course we don't, if we don't make any effort, there are no way for the good fortune to come with us.