In shakespears Macbeth, the weird sisters are only one of the contributions to Macbeth's destruction. Though they do play a role, the other characters such as Lady Macbeth and even Macbeth himself contributes towards his destruction, with immense ambition and greed to become king.
The prophecies which the witches make are only temptations for Macbeth. The weird sisters never tell Macbeth what to do with these suggestions, he just becomes curious and disbelieving about what the witches say, though takes their forecasts literally. The witches only make predictions about the future kingship of Macbeth: "All hail, Macbeth! Hail to thee, Thane of Cawdor."
Macbeth, along with Lady Macbeth take the prophecies to in-depth and try to implement them as soon as they desire. The prophecies predicted by the weird sisters do occur in the end, but somewhat not how they wanted.
After Lady Macbeth is told about the prophecies foretold by the witches, want for power seems to over ride her and take control. Lady Macbeth devises a plan for Macbeth, so that he must kill Duncan who is king at the time, she expects Macbeth to accept, as their ambition for power is greater than each others. She treats Macbeth as he isnt man enough to take this plan to action and confronts him and tells him he isnt born of man. Though Macbeth accepts the plan to Kill king Duncan, but Lady Macbeth starts to feel guilty for the actions that had been taken and her guilt leads to death of her as she falls out her bedroom window.
As Macbeth takes Lady Macbeths plan, his want for power is high at this point, not taking into reality what he really is doing. After Duncan is dead, Macbeths ambition has come alive and now really all is done in his eyes. Though with Malcom in anger, he grasps some help from Macduff, whom meets with Macbeth in town to have a fight. Which Macbeth looses causing all destruction upon himself and dies, which