There are many conflicting opinions about Macbeth's responsibility for his own downfall in Macbeth and whether he should be held fully accountable. Having a fatal flaw and being rendered not responsible otherwise creates a tragic hero. To deal with his own responsibility, Macbeth has many opportunities to see the error of his ways; in fact, as the witches have accurately forecast his rise to position of Thane of Cawdor, he has no reason to doubt the remaining prophesies. "...to be King stands not within the prospect of belief, no more than to be Cawdor."(I.iii.74-75)
Macbeth is aware that "vaulting ambition, which o'er leaps itself" I.vii.27) is his only reason for plotting to kill Duncan who does not deserve this cruel fate as "his virtues will plead like angels."(19)He has made his decision and "will proceed no further in this business."(32)As a decorated soldier, he knows the value of good, sound decision-making and so does have the capacity to recognize that it "cannot be ill; cannot be good."(I.iii.131)
Even having murdered Duncan, Macbeth can now revel in his Kingdom. He has his wish and can make his plans and ensure he is not discovered as "false face must hide what the false heart doth know."(I.vii.82) However, his lack of self-control leads to Banquo's death and the steady decline of Macbeth to the point where he fails to recognize the "juggling fiends," the witches, for what they really are.
Therefore, due to all the opportunities to either stop himself or stop short of destroying himself and mainly due to his recognition of his own weaknesses, Macbeth should have had the strength of character to defy his wife's attack, suggesting what makes him "so much more the man"((vii.51), and do the right thing. He knows his ambition is trouble; he knows the witches create situations where "fair is foul and foul is fair" (I.i.10). He could have risen far in the ranks by being patient and he knows the value of honesty and integrity which presumably got him this far.