I find there are two reasons the people who are comfortably rich spend money. We are not talking about the nouveau riche, or the fake rich, trying to spend money to act rich. We are talking about the people who are comfortable being wealthy. They spend money for either quality or convenience. It does not have to be a lot of either, just a nominal amount of either.
So a rich person would have no trouble getting eggs at Publix, assuming it is more convenient than other supermarkets, and that they do not want some special Whole Foods free range Omega something eggs.