Well, historically, among the Western working class (which was most people), you worked as long as you were physically able, then your kids (now adults) were responsible for your upkeep, if your own resources were insufficient. This is one reason why older houses are so large. Not only were families having more kids, but there also needed to be room for a grandparent or two, and possibly an old drunk uncle who couldn't hold a job for more than fifteen minutes. It was EXPECTED that Grandma would come live with one of the children when the time came.
But this system broke down in many cases, which is why social security was implemented - to keep the elderly from being destitute. 65 was chosen as the "retirement" age because it followed a similar program in Germany. Of course the average lifespan at the time was about 65.
I know a lot of people who simply don't have the resources to support themselves in retirement, even with social security, and I feel sad for them. It's a pity.
What I don't understand is people who HAVE the resources to retire, and yet continue to work. I just don't get it. I've been retired for two years and even though I "liked" my job, someone would have to take me kicking and screaming back to an office to do any more of it (I do volunteer stuff when I feel like it).
I personally think such people have a distorted view of the decision process. They think (and I've heard many of them say), "I have no reason to retire." If they have no "reason to retire" then they keep working.
But this is upside down. The actual question should be, "Is there any reason to keep working?" If not, then retirement is the "default value," and should be taken.