#1. Former WWE Superstar Braun Strowman
WWE is well known as the "Land of Giants." Giants have always been a cornerstone of wrestling, WWE or otherwise. Big Daddy Haystacks, Yokozuna, Andre the Giant and The Big Show were all being incredibly popular in their time.
But then along came Braun Strowman, a giant with an unnatural amount of agility and athleticism who could switch between being a believable, unstoppable force to a believable comedy act. In short, he could do anything that was asked of him.
A top AEW star just called one of his colleagues 'spoiled' and 'narcissistic' HERE.
WWE did definitely see some potential in Braun Strowman as he did eventually win a world title (albeit because Roman Reigns' absence caused plans to change) but every single time they seemed to finally be putting Strowman at the top where a man of his size and talent belonged, they somehow managed to take two steps back with him.
Strowman is the closest thing to a sure thing in professional wrestling, and yet somehow WWE managed to squander him and ultimately ended up releasing him.