Because people (investors included) are not rational individuals, and tend to warp the information they are exposed to in order to fit their preconceived notion

Because people (investors included) are not rational individuals, and tend to warp the information they are exposed to in order to fit their preconceived notions and values. They valorize the overworking founder with no personal life, and have grown up with not-so-accurate tales of the Big Names who were like that. And so you get quite sincerely held but incorrect beliefs that are shockingly resistant to evidence. Welcome to the human species.