There's a self-selection here.
Anyone with any sense, or sense of their mortality, selects their selves out. I've met some and wondered how they could do some things. You are correct, it doesn't occur to them that they could die.
Even so, they don't seem to take chances they don't have to. They have good equipment, they use it appropriately. I've seen 'em practicing knots they already know, practice tying them one-handed, in the dark, anything to ensure competence.
I know they wouldn't do it if they felt the fear I do just looking at it.