It's funny - I've only caved a bit, but I watch that video and think "wow that looks fun." There's something so exciting about getting right up to the edge of what's possible for a human to do.

I know what you mean, I went through a fairly simple cave except for ~90 feet with 3 90 degree turns in between which required me to be completed stretched out (Superman style) and push with only my toes/fingertips. It was terrifyingly exhilarating.

when I was a kid a crawled into half collapsed etruscan tombs often (which in hindsight was not a good idea) and it felt ok but this video gave me instant claustrophobia.

It's incredible that people can do this as a hobby :)

I’m going to have nightmares after seeing that gif. How can these people be ok with that?

Also, does the notion of eventually needing to turn around never stymie them?

That's why the send the cameraman first.