https://fortune.com/recommends/banking/57-percent-of-america...
And certainly some people never did manage to save $600,000 over the past 40 years, but it remains that the bar does not seem that high. Even the lowest bar will not be met by some people, but that doesn't mean the bar is high.
In any case, if you want the categories separated, here you are:
In 2019, about half of American households had no savings in retirement accounts, according to the Survey of Consumer Finances (SCF). These accounts include individual retirement accounts; Keogh accounts; certain employer-sponsored accounts, such as 401(k), 403(b), thrift savings accounts; and pensions.
We're looking at those who have 20 years left, not those who could have 60 years left. Naturally one could avoid saving anything for 39 years and then plop down a $600,000 lump sum in the final second and you would be in the exact same place as someone who slowly amassed $600,000 over the span of 40 years, so half of the population having nothing saved doesn't tell us anything.
Bringing us back to the actual topic: Of those who have 20 years left, how much do they have saved?
Sure, they could for example win the Powerball.
The median American can afford to save considerable money but they tend to spend it on lifestyle flexes instead.