One interesting issue in life span development is how age-related changes in different core abilities, like attention, memory, and so on, impact achievement in the real world, such as everyday financial and health decisions. Many areas of performance show an inverted-U shape across the life span, with improvements being typically seen during adolescence and young adulthood, and decline being more often than not observed in older age. I just read that Forbes has a new list of billionaires and that got me thinking whether such a pattern exists for such things as wealth?

I took the data from Forbes (N = 1762 for which age and net worth was available) and, as can be seen below, the mean age of billionaires is around 60. There could be a number of reasons for this but one likely factor is that it takes time to accumulate wealth (Forbes writes that the majority of millionaires, ca. 1200, are self-made billionaires with the rest having inherited their fortunes).

But does wealth show an inverted-U like shape across the life span? The Forbes data suggest it does not. It looks like there is a positive correlation between age and net worth, suggesting that old age does not lead losses in accumulated capital… In this way, capital seems to work a bit like the accumulation of knowledge which tends to show a gradual increase across the life span.