Mr. Rich admits the almost surreal meaningless of their excess wealth.
Which he's just placed in the hallway for some reason.
Just because the strongbox is shaped like the dollar doesn't mean it couldn't hold coinage, does it? Unless Mr. Rich has a thing about coins, and banishes them from the grounds. Perhaps he's just pointint out that the safe does not contain coins, as a point of information, and its shape is irrelevant.
Richie seems to think Dad's made a funny, though.