Falling in a dream and waking up before hitting the ground is due to the instinctual panic that a dream fall causes.
When you’re falling, your brain knows that the longer you fall, the less survivable it gets. It’s crucial to stop your fall within a short time, and if that’s not possible, then death quickly becomes inevitable. Your dream will usually either shock itself awake at that point, or drag out the fall indefinitely until you awake to avoid the impact (or just make you invulnerable so you survive anyway)
So, what does completing the fall and dying mean? There are a few possibilities: 1) your brain skipped over the actual fall, and just jumped straight from “you fell” to “you died”. This might seem a bit implausible, but the fluid logic of dreams can skip over stuff like that. 2) this one’s more likely, given your claim that this is a regular occurrence: the fall didn’t kick in that instinct that wakes you up. It’s possible your brain is desensitized to the concept of dying and doesn’t fear your own death, or it’s possible that some part of your subconscious knows it’s a dream and there aren’t any real consequences. Given the fact that it switches to third person to keep going after you die, this might seem more likely, but this may just be the dream continuing the “story” with you as a “ghost”.
It’s quite possible for one’s mind to adjust to this. I’m not sure how reading sci-fi/fantasy might cause it. Many years ago I had a dream about driving with a bomb, and woke up before it went off. Years later, I’ve had at least two dreams where I’ve died and the dream switches to third person. At some point in the interim, my subconscious has lost that instinct. In my case, my brain has become more “practical” – me dying won’t matter to me, and will only matter to those who know and care about me, so it loses that fear, even if it is still an outcome to be avoided.
Anyways this is the part where I try to throw in some levity by saying “last night I dreamed about _”, except my dream was actually kinda boring, so I’m just going to pretend that I dreamed about sword-fighting a T-Rex on top of a Helicopter.