How can Macbeth's famous "Is this the dagger which I see before me" soliloquy be adapted into a modern-day scenario?

One of the most important aspects of this soliloquy is that Macbeth only hallucinates the dagger, clean at first and then bloody, because he is so internally conflicted about killing Duncan.  He recognizes that it is a hallucination of his "heat-oppressed brain" because when he tries to grab it from the air, he cannot.  Shortly after he hallucinates this dagger, he tells Lady Macbeth that they "will proceed no further" with their plan.  Thus, we...

One of the most important aspects of this soliloquy is that Macbeth only hallucinates the dagger, clean at first and then bloody, because he is so internally conflicted about killing Duncan.  He recognizes that it is a hallucination of his "heat-oppressed brain" because when he tries to grab it from the air, he cannot.  Shortly after he hallucinates this dagger, he tells Lady Macbeth that they "will proceed no further" with their plan.  Thus, we know that Macbeth feels very guilty about killing Duncan, his friend, relative, guest, and king.  

So, if you can come up with a modern scenario in which someone really doesn't want to kill someone else (and even sort of feels guilty about it) but is ultimately willing to do it because it would confer a great deal of power on them, this would be appropriate.  Perhaps you could consider the recent big lottery winners as a starting point.  What if one of the winners (Duncan) has a greedy brother (Macbeth) who really doesn't want to commit murder (maybe he even loves his brother) but he really badly wants to get that money.  He thinks that, once he gets the money, he can pay off all his debt and pay for his kids to go to college and improve his life so significantly that he is, finally, willing to commit the murder because he believes the money will improve his life so greatly.