http://www.npr.org/blogs/money/2012/08/01/157664524/how-the-poor-the-middle-class-and-the-rich-spend-their-money

Data from the Consumer Expenditure Survey point out some specific differences in how poor, middle-class, and rich people spend their money. The less money you have, the more (proportionally) you have to spend on immediate needs (food, housing, utility bills, transportation, medical care), and the less you have left for long-term goals (education, retirement savings).