> For its part, the Deutsche Bank report explicitly defined luxuries as goods or services consumed in greater proportions as a person’s income increases and necessities as those goods or services that make up a smaller proportion of spending as a person’s income increases.
> It’s worth noting that by the specialized nomenclature of the dismal science, even eating at McDonald’s is a luxury — that is, we do it more as our incomes rise — while smoking and lottery-ticket buying are categorized as necessities.