The average item bought by the average buyer has an income elasticity of nearly one: most people roughly double their spending when their income doubles. But everything we buy consists of both a quantity dimension and a quality dimension.
What’s clear is that the income elasticity of demand for quantity is less than one: when our income doubles, we don’t double the number of cars we buy, the number of beers we drink in a day, or the number of houses we own.
The income elasticity of demand for quality must therefore be more than one: as our incomes rise, we increase the quality of what we consume. We shift from Honda Civics to Lexuses (Lexi?), Budweiser to Belgian dobbels, prefab houses to mini-mansions.
The reason is simple: it takes time to consume quantities, while the consumption of high-quality goods takes no more time than low-quality goods; and as we get richer we have no more time — we all face 24 hours in the day.
With incomes rising over time, businesses are smart to bet on the demand for quality rising — and to enter markets where the payoff is to quality not quantity.