"Everest" is based on a true story. The screenwriters and actors did a great service to the book and alpiners, it was not over-acted or over-dramatized; no exploitation or gratuitous BS like in so many other action movies. True to the story and an honor to the climbers who survived, those at base camps that assisted, and those that died.
No one quite understands why humans need to push themselves, but to me, it's about escaping the daily grind and coming to a place where your focus is so completely on a singular action, that there is nothing but the next move. Whether it's the next move on a wall or cliff while climbing, or being so absorbed in the sensations and sights 140 feet below the sea's surface; it's the focus required that takes every bit of mental and physical energy. There isn't a thought of danger or death; you are just absorbed completely in them moment. It's a gift to that focused, akin only to time in meditation, but harder to attain in meditation for sure.
I feel the same when I'm pushing myself on my bike, weaving through traffic: all of my senses are focused. My eyes on the road in front of my tire while simultaneously seeking out cars trying to target me, listening for cars I can't see, legs, lungs, and heart all pumping.
Is it a "thrill" to carry out dangerous activities like climbing, cycling, diving, flying a plane, surfing, hang gliding, etc.? Well, I would lie to say no-- of course it is. This is some of the attraction. That thrill concentrates focus so severely that it truly becomes a release from minutiae and, as the obnoxious Texan said in "Everest" when asked why he needs to summit mountains, it is truly an escape from the "dark cloud that follows" us.
This is why I do what many of you call "high risk" activities; I love the focus and the challenge, and yeah, it helps me temporarily escape the "dark cloud" that follows me.