"When all is finally entered into the annals of sociology; when philosophers, politicians, and preachers have all had their say, we must return to the fact that a person participates in this society primarily as an economic entity. At rock bottom we are neither poets, athletes, nor artists; our existence is centered in the fact that we are consumers, because we first must eat and have shelter to live. This is a difficult confession for a preacher to make, and it is a phenomenon against which I will continue to rebel, but it remains a fact that "consumption" of goods and services is the raison d'être of the vast majority of Americans. When persons are for some reason or other excluded from the consumer circle, there is discontent and unrest."
Source: p. 295 in The Autobiography of Martin Luther King, Jr. Edited by Clayborne Carson (1998). Grand Central Publishing. In this part of the book is King's reflection on the 1965 Watts rebellion in Los Angeles. King went to Watts a few days after the rebellion ended.