Movies are about a protagonist or a group of protagonists who ultimately change over time.
They evolve.
Books, too. Most television shows, also. So, too, for plays and Broadway musicals.
All stories are about change. Our protagonist or protagonists begin in one place but end in another.
This is why so many self-actualized movie characters die. They have no place to go. They represent fully evolved, self-actualized human beings, and therefore, the only place to go is the grave.
Some begin the movie self-actualized. Some reach self-actualization over the course of the film or many films. Either way, once they reach that pinnacle of human perfection, they must die, or the movie must immediately end.
But if they start the story as self-actualized characters, they will likely be dead before the end of the story.
Characters who begin the film already self-actualized include:
Jack Dawson in “Titanic”
Captain Miller in “Saving Private Ryan”
Obi-Wan Kenobi in “Star Wars: A New Hope”
Maximus in “Gladiator”
Harry Stamper in “Armeggedon”
A handful of characters in Star Wars “Rogue One”
Spock in “Star Trek II: The Wrath of Khan” (though he returns to life in the next film)
All of these characters were perfect to start. No need for improvement, so the only evolution available to them was death.
Others reach self-actualization by the end of the story and, therefore, die. They include:
Tony Stark in “Avengers: Endgame”
Thelma and Louise in “Thelma and Louise”
Batman in “The Dark Knight Rises” (though it appears he may be alive after all)
All of these characters had reached their peaks. They possessed confidence, skill, courage, wisdom, and everything else we imagine in a self-actualized person. No more growth was required.
But in the end, each was flawless. Therefore, they needed to die.
Of course, this isn’t always the case. Many self-actualized characters live to fight another day — often in a sequel — though most who begin a story already self-actualized will die by the end of the film.
But if you like your heroes to survive, you should hope that your protagonist remains a bit flawed at the end of the film.