Thomas Sowell said this quote

What sense would it make to classify a man as handicapped because he is in a wheelchair today, if he is expected to be walking again in a month, and competing in track meets before the year is out? Yet Americans are generally given 'class' labels on the basis of their transient location in the income stream. If most Americans do not stay in the same broad income bracket for even a decade, their repeatedly changing 'class' makes class itself a nebulous concept. Yet the intelligentsia are habituated, if not addicted, to seeing the world in class terms.