Working right up until death-- frequently preceded by a fast terminal illness-- was the norm throughout most of human history. Many families had a couple elders who were no longer able to work due to blindness or other things they couldn't treat at the time, but they were supported by their children or grandchildren and frequently if they had no families they relied on religious institutions or the kindness of strangers.
Having years, or even decades, of leisure time to be enjoyed in a relatively able-bodied fashion didn't become the norm until very recently. Our modern post-industrial society is so affluent it's almost otherworldly compared to how human beings got by throughout history. An average family lives better than many of the medieval nobility. We perform less physical work, have more living space, enjoy more luxuries and have a longer lifespan.
There's a chance that the near-universality of retirement could be an economic flash in the pan much like the way it was briefly possible to support an entire family at a comfortable standard of living on just one income without requiring credentials beyond high school. Mustachians and other statistical outliers can still pull it off, of course-- and there will always be statistical outliers who can-- but the economic circumstances that allowed such conditions as the viable single-income nuclear family to exist in such large numbers as to become the norm turned out to be temporary.
