I find that amazing, given how little SS pays. I wonder with how many of those it's because they're older and tapped out their savings when they went into assisted living. For example, if you get Alzheimers and get to the point where you need constant nursing, the cost of a private facility that will do that is ruinous, and will quickly deplete even a well-stocked 401K and any home equity you had. At that point you can basically become a ward of the state, with your SS and Medicare/Medicaid covering the cost of a public nursing facility. With the astronomical cost of medical care in this country, only the very rich are really safe from that.
In my own case, short of that kind of ailment, I'm in reasonably good shape for staying comfortable in retirement. I have already vested into a pension that is worth something like $30k per year (it'll be more by the time I retire, if I stay at this employer). That'll only be worth the equivalent of maybe $10k-$15k per year, by the time I get there, because of inflation, but if SS covers the basics of life, that's enough for me to have a few little luxuries on top of that (and occasional trip to see the grandkids, etc.), so that's nice to have locked up.