But the essay, such as it is, was about usefulness or uselessness, not money. And in any case, there are hundreds of millions (more probably billions) of humans on this planet who neither have nor need money. Your concept of retirement is narrow and necessarily bound to a particular mode of living, as well as largely unrelated to whether someone is useful. The idea that the three phases of life are childhood (idleness), employment (saving money), and retirement (spending money) is both historically and culturally anomalous. It's more constructive to think about the many modes of living and their relationship to one's personal utility and sense of worth than to dwell on labels, especially since so many people live in ways that are hybrids or entirely outside the system your labels assume.