The study participants, college students, represented an extremely small, very exclusive slice of the population compared to today. The "elites" we would call them now.
This is the common problem with nearly all published psychological studies that come out of universities, they basically only study the sample most available to them, other college students, and that was an even less representative sample than it is today.
Jesus christ. Give a medal to the guys who designed that fire-retardant suit. Video makes it seem like longer, but even the actual 20 seconds he spent in that inferno is insane.
Not a video, but hopefully you can forgive for context: