Have you watched all the people who don't make it?

I don't think that's acting.

My understanding is that it's one of the most realistic reality shows out there. They're not truly alone but other than providing medical care and evacuation should they tap out the crew pretty much doesn't intervene. (And if they do it's things like one guy who didn't give a hoot about the nudity and they asked him to be a bit more discreet because it was making things so hard on the camera crew to get stuff that could be aired.)