On many levels I agree with you. But, you can also look at this thru the paradigm of the "hero's journey". A normal person, plucked from the masses is given a harrowing mission. If they survive, there is glory ($$$), if not, then there is failure (Internet ridicule).

Granted, Mr. Beast is not giving us the story of Luke Skywalker, but I can understand the rational of the person taking the challenge.

For most people watching, it's just torture porn, but content providers have to give the people what they want to make a buck....