Jimminy sufferin Crickets; Arthur Brooks is human refuse. His "peak" means "peak shilling for oligarchs and foreign moneybags trying to foment useless wars." Really, his time has passed because we (left and right) are done with your neocon bullshit.
Reading the actual article (not necessary, but I suffer for you): he mentions ... athletes, who of course mostly peak early, Darwin (who has no comparison class; gee, sorry he didn't think of his theory after he was 50), Dirac, Bach, poets... and how we should meditate on death.
What this is is typical Brooks oligarch shilling. Be happy with less, peasant; your value declines as you age. One of the other weasels at AEI will doubtless write something about how young employees are similarly worthless.