What are some examples of Macbeth being a victim of circumstance instead of a villain?

Macbeth is a classic example of a tragic hero. His own
character flaws ultimately lead to his downfall. That's the important thing here - there
are certainly some examples of Macbeth being a victim of circumstance, but he ultimately
did himself in with his greed and ambition. These traits were inherently his.
Circumstances may have influenced him greatly, but they did not make him greedy and
ambitious.

Examples of being a victim of
circumstance:

1. The prophecy of the three
witches

In Act I, Scene III Macbeth and Banquo encounter
three witches who make some very intriguing claims. They tell Macbeth that he will be
king. This idea immediately fills his head with wonderment and ambition. He's clearly
excited about this notion, but it's also obvious that he's not sure how to act on it, or
if he will even act on it at all. We see his internal struggle with his natural ambition
and greed against his thoughts of kindness and honor. Had he never encountered these
witches and heard their prophecy, he may never have thought of striving to be king of
Scotland.

2. Lady Macbeth's ambition and influence on
Macbeth

Macbeth's ambition is only outdone by his own
wife's ambition and greed. She desires the finest things and the highest status. When
she learns of the prophecy, she immediately begins working on manipulating her husband.
It is her idea to kill King Duncan and she wastes no time in pressing this idea on
Macbeth. When he hesisates at the idea, she responds by mocking him and questioning his
manhood. "When you durst to do it, then you were a man" (Act I, Scene VII). Lady Macbeth
goes to the lengths of concocting the entire plan to kill Duncan, even how to cover
their tracks. She manipulates and nags her husband until he reluctantly agrees to carry
out the evil deed. Without Lady Macbeth's influence, would Macbeth have murdered Duncan?
You could argue that he would not have since he was very uneasy about the idea in the
first place and repeatedly tried to back out of it.

3.
Macbeth himself

We've established that Macbeth had certain
inherent qualities - he was greedy and ambitious. Could he control those urges within
himself or was he predisposed to be that way? We saw what happened once a seed was
planted in his head (that he'd be king). He killed Duncan, killed his best friend
Banquo, killed the family of another friend, and turned his entire country against him.
His greed and ambition turned to stubborness and he died because of
it.