Who is responsible for Macbeth's downfall and his death?

is
wholly responsible for his destiny. He should take the blame for whatever happened to him. The
fact that he was driven by ambition was a choice he made. 

When we meet him,
we hear about a soldier who is loyal and courageous. A man who was driven to defeat his
country's enemies and utterly destroy them, whatever it took. He receives generous praise and is
rewarded for his noble actions. 

We soon learn, however, that he harbours a
pernicious desire to achieve the Scottish throne by illegitimate means. He admits that he is
driven by 'vaulting ambition' which clearly indicates that he does not wish to ascend by having
to follow the natural rules of succession. His desire is to become king as soon as possible, by
hook or by crook. When he andmeetand they greet him by a new title as well as inform him that he
will be 'king hereafter', he is sceptical untiland Angus arrive.

When Ross
informs him that he has been awarded the title thane of Cawdor as the witches...