It is possible that choosing to work past the age of retirement, can actually help some people live longer.
It is possible that they are making a very wise decision to do so. Working longer could help people to live longer, as Harvard Health Publisher discusses in "Working later in life can pay off in more than just income."
Staying active helps keep some chronic illnesses at bay. For example, the social and cognitive abilities necessary for some jobs helps stave off dementia. This does not mean people should avoid retiring or that they need to continue to work 40 hours a week, until the day they die. What it does mean is that it is important to stay active, both mentally and physically, as long as people can do so. Part of that mental activity can include some work.
Continuing work is not for everyone. It is typically not a good idea for people whose jobs have a physical labor component. Consult with a doctor to make sure that you can still work, if you are considering doing so past your retirement age.
If you are concerned that you do not have enough money to retire on so that you have to work, then talk to an elder law attorney about your other options.
Reference: Harvard Health Publishing (June, 2018) "Working later in life can pay off in more than just income."