Why did Macy character need the $?

Rating: Null/10 (28 August 2005)

I love this film. One thing it never reveals is why the Macy character badly needed so much cash in the first place. First, this need for cash leads to the fraud with GMAC Financing (early in the film), but then, of course, it leads to the series of events in the main plot of the film.
Anyone care to guess what the Macy character did to need so much cash, so quickly? We see no substance abuse or gambling tendencies. I'm stumped.
One minor gripe with the film: the "true story" bit. It isn't. I don't understand why the Coens would feel the need to make that up, but they did.