Because they didn't get rich paying full retail. The guy flashing a roll who wants to pay top dollar probably doesn't have anything much except that roll of bills.
Although my experience has been that the people that have real money generally don't drive Ferraris or Bentleys. More often it is something in the $50 - $80,000 range.
I know a guy who had a Maserati. He can barely make the payments, spends the rest of him money on flash. Gets the girls... until they discover that he doesn’t have a pot to p1ss in outside of the fancy impressive toys.