Or art but a dagger of the mind, a false creation. (2.1.33-38)
Macbeth also see's visions of Banquo's ghost. After others realize that Macbeth "play'dst most foully" for the crown they lose their respect for Macbeth. He is called a "tyrant" by a lord, also "devilish." "Cannot buckle his distemper cause within the belt of rule." (5.2.15) This "belt" he is trying to buckle is his "borrowed" title as king that he cannot control. Macbeth may have been told he would get the crown, but does not mean he will be a good king; instead, he loses his friends and supporters. Macbeth makes a complete transformation; he no longer thinks, but acts on impulse, and "The devil himself cannot pronounce a title more hateful" (5.7.7) as the name Macbeth, he is purely evil. Macbeth's robe "hang[s] loose about him, like a giant's robe upon a dwarfish thief" (5.2.20-22); he no longer is respected and has lost all compassion, making him unfit to be king, a title he stole in the first place. He kills Banquo to protect his secret of murder, also, kills innocent lady Macduff and child.
Macduff said, "The tyrant has not battered at their peace" (4.3.178) then Ross turns around to say, "For I saw the tyrant's power afoot"