Given the assumption that someone accumulates about 507k by 65, 4% of that is roughly 20k per year, which, without having other assets like a home, would prove to be very difficult to live anywhere in the US on.
This is all true, but it's also not really germane to the point I was making. I didn't include anything to account for the fact that as people get older, they also tend to be able to save more towards their accumulated wealth, which would amplify the disparity between younger and older generations even more. As you note I ignored real-estate assets, which again you would expect older generations to own and own more of relative to their younger cohorts. One could also quibble about my decision to use 4% and 7% as the example ROI numbers.
But I would point out that given that I did ignore a number of factors that should skew the wealth distribution even more towards the older generations, one could argue the fact that the numbers played out as close as they did to just a basic simple 4% annual to retirement and 4% down in retirement calculation means that younger generations are actually doing better now than they should be doing. Of course we would need to look at where the wealth we expect the older generations to have has gone to say for certain but in either case, the original quoted numbers don't seem nearly as terrible as they appear at first read.
If you're a couple that could mean two stream of social security income and if you've paid off the 30 year mortgage by the time youre 65, your major expense is gone.
So you're at $60k income and low housing costs. Doable for sure.