Why is that odd? When did you make most of the money in your life? Before your 30th birthday, or after?
Workers is not as important as earners.
You can't magically have a 20 something doing the same thing a 40 something was doing, for the same quality. Let alone a 30 something and a 50 something.
The death of a 50 something takes more out of the economy NOW and for the next 10 years than the death of a 20 something. Longer than that, sure. But that then extends the economic recovery by a similar number.
I believe that the primary/peak income-earning years (not the same thing as wealth-earning, but I digress) are 40 - 60.