Macbeth's ambition ruled his actions and led to murder. His ambition was to become king. Many people died and were killed because of his ambition.

At the present time Duncan was king. Since Macbeth wanted to become king, he decided to kill Duncan. Macbeth sets out ahead of him to prepare for Duncan's royal visit. When Lady Macbeth learns that Duncan is coming to visit, she takes charge. She tells Macbeth that she will prepare for Duncan's visit and for his murder. As Duncan arrives at their castle, Macbeth gets scared and does not want to go through with it. Then Lady Macbeth signals and Macbeth exits to kill Duncan. Ross announces that Macbeth will become king. "The sovereignty will fall upon Macbeth" (2.4,42)

Banquo becomes suspicious about Macbeth becoming king. Banquo thinks that Macbeth was the one who killed Duncan. Macbeth then makes a plan to kill Banquo. He hired two murders to kill him. He invites Banquo to a feast, where the murders will kill him. Macbeth told the murders to kill Banquo and Fleance. However, Fleance escaped and they killed Banquo. His ghosts showed up at the feast and the ghost nerved Macbeth. He was guilty.

Macbeth discovers that Macduff has fled to England, so he decides to go kill his family immediately. As a messenger arrives to warn Lady Macduff to flee, before she can do so, Macbeth's men attack her and her son. Then Lady Macbeth kills herself because of the guilt she has about Banquo's death. "Out damned spot, out, I say!" (5.1, 37) "What's done cannot be undone" (5.1,71) Then the Scottish forces join to come against Macbeth. Birnum Wood marches on Macbeth's castle. Macduff killed Macbeth and Malcome was declared king.

Therefore, as you can see, Macbeth's ambition drove him too far. He ended up getting his self-killed, loved ones, and many more. You should never let something you want so badly make you do something stupid and go all out of your way for it.