This morning, I found a note from three years ago about "I Wanna Be Rich" that I finally got around to looking into. In the choruses, the word "Money" is sung by the backing vocals for almost two full measures at a time (four times total), and this long duration illustrates the prominence that money has for the narrator.
I also had a couple related realizations: the word is sung to only a single pitch (a G), showing money's primacy in the narrator's thoughts, and its repetition and duration match the great amount of money that the narrator desires ("Money, money, I want a lot").