How does Macbeth's obsession with the witches lead to his downfall?

When Macbeth discovers that he has become Thane of Cawdor just like the witches prophesied, he cannot help but dwell on the other part of the witches' prediction -- whether he will become the king of Scotland or not. However, Macbeth succumbs to the destructive power of his ambitions and takes matters into his own hands. He does not want to wait to become the king lawfully, instead, he is the one who wants to...

When Macbeth discovers that he has become Thane of Cawdor just like the witches prophesied, he cannot help but dwell on the other part of the witches' prediction -- whether he will become the king of Scotland or not. However, Macbeth succumbs to the destructive power of his ambitions and takes matters into his own hands. He does not want to wait to become the king lawfully, instead, he is the one who wants to fulfill the witches' prophecy. When he murders Duncan, we observe the beginning of his downfall. On the inside, he quickly becomes an unstable and vulnerable person, afraid he might lose his position as the king of Scotland. The reason for his unsettling thoughts lies in the fact that he feels threatened by the second part of the witches' prophecy, which states that Banquo's descendants will inherit the throne some day. This perturbs Macbeth greatly, and he begins to murder anyone who he thinks may jeopardize his position as the leader of the country.

Impatient to find out what awaits him in the future, he seeks out the witches and demands to find out what will happen. This shows how desperately dependent he has become on the witches because he does not want to allow nature to take its course. He wants to feel safe and immune to any threat and fear. However, his trust in the witches only shows how oblivious he is of the fact that their prophecy has a very destructive effect on him. He takes their words too literally, believing there is no such thing as a man not born of woman or woods that can move.

Although Macbeth is seduced by the witches' prophecy, the witches are not responsible for his downfall. They only sensed how corrupt he can become and encouraged such behavior. However, Macbeth's unbridled ambition is what makes him transform from a valiant and loyal subject to a treacherous and cold-blooded murderer.