Gladwell is right that there is prejudice in certain fields (although he only mentions lyric poetry). For example, in music - jazz and classical, anyway - if you’re not discovered by 25 (Young Lion), your next chance will be in your 70s (Old Master). In between, you simply don’t fit any easy category for promotion, and you give schooled musicians cause to doubt your talent, because they all take their training young.
I love the example of Paul Winchell, who was a beloved ventriloquist entertainer when I was a kid, as well as the voice of Disney’s Tigger and other cartoon voices.
He had a whole other career in his older years in medicine, though, never got an MD.
From Wiki:
Remarkable that someone in mid life would switch from a successful entertainment career to exploring innovation in medical realm. I do know that there is some debate with Winchell/Jarvick on the artificial heart claim. It’s not my intent for this to devolve into a debate about that.