How does Macbeth's poor decision making influence his doom?

One of the most fascinating aspects of Macbeth is that, though Macbeth's future is presented as if fate were guiding it, there's also the suggestion that Macbeth's poor decisions influence and bring about his downfall. For instance, consider Macbeth's behavior after he gains the crown. Though it would appear that Macbeth is initially liked by most of his followers (or, at the very least, he's not disliked), Macbeth becomes increasingly paranoid and embarks on a murderous rampage to quell his fears, first killing Banquo, and then murdering Macduff's family. By doing so, Macbeth rightly earns a reputation as a tyrant, and his formerly loyal followers begin to plot revenge. By extension, we can see that Macbeth's paranoid and tyrannical behavior (his poor decision making, in other words) directly leads to the rebellion of his noblemen and his eventual demise. In that case, even if fate is at work in the play, it's also clear that Macbeth's poor decisions play a huge role in bringing about his downfall.