The poor spend relatively more on what will keep them alive, because they must, and the rich spend more on what will keep them rich, because they can.
Each year, the U.S. government tells Americans how much money the country spends on stuff, like houses, cars, and alcohol. Organizing this information by income, Josh Zumbrun at The Wall Street Journal produces this nice chart of spending on food, health care, and other categories.
Share of Spending on Certain Categories, by Income Group
Two clear stories. To the far left: The richest 10 percent spend much less of their income on food. To the far right: The richest 10 percent spend much more of their income on insurance (and relatively more than all but the very poorest on education).
When you have money, you spend less on the stuff that ensures you survive the day and more on the stuff that ensures that you (and your children, and your possessions, and your estate) survive and thrive for many years. Poverty is a chaos that screams in the present tense, and the anxiety of having no money forces poorer families to direct their attention to immediate concerns. As a result, the poor spend relatively more on what will keep them alive, because they must. And the rich spend more on what will keep them rich, because they can.