Quote from Scientist:
Good question. Both are pretty awesome achievers. Tom Cruise for example, has never let a stuntman do a job for him. He even insisted on doing the freeclimbing part in a movie himself, where he was like hanging off a a rock ceiling really high up, with no support and bare hands. One slip, or a cramp, and he would have been dead. The film crew and the producer freaked out completely, but he said he'd either do the scene himself or he'd leave the set right there and go. Wasn't it "Cliffhanger"?
If you actually believe that promotional crap they feed you then you're a fool.
The movie was mission impossible. And the close-ups are all done in studio. The backgrounds are computer generated.
You're right about no support though. You don't really need any when you're 2 feet off the ground.
Do you really think the insurance company of the film are going to risk losing $300 million if the star dies mid way through production. Not a chance.
The only guy that ever did his own stunts was Jackie Chan. And he used to finance most of his own movies without insurance.
