dazed and confused

I can't sleep. And I've been staring at this New Yorker cartoon until being forced to the conclusion that I don't get it. If you get the joke, can you explain it to me?

Update, 7PM: Okay, so the consensus is that the joke is that the guy who has the big bag of money should be content with his bag, but instead he is still trying to get even more money by asking the guy with the little bag where his money came from.

Most eloquently, a reader in Glim Cocoon, NY writes: "the joke is that the Bald White Guy with the huge bag of money wants to know where the BWG with the small bag of money found said small bag, presumably so that Big-Money BWG
can get some to add to his stack. At that point, the cartoon becomes a trenchant comment -- and an oh-so-hilarious one, too -- on greed in contemporary capitalist societies."

This did occur to me as possibly being the joke but it seemed, as it did to the above and other readers, really lame. Besides which, it also seemed like basically a general reflection of what people with giant bags of money do--still try to get more money.

The Glim Cocoon reader posited that the difficulty in figuring out the joke stemmed in part from the confusion as to whether the "get" or "that" in the caption should be read with emphasis. She gets a bonus prize for going on to include an example of the power of emphasis from the movie Passion Fish (which chronicles the violent final hours of a pescomessiah's life):

A young soap opera actress is practicing her line, "I didn't ask for the anal probe," and tries out various options:

I didn't ask for the anal probe.

I didn't ask for the anal probe.

I didn't ask for the anal probe.

I didn't ask for the anal probe.

I didn't ask for the anal probe.