For Roland, it’s to ensure the continued safety of The Dark Tower.
The Dark Tower is set for release on February 17, 2017.
Bringing on Idris Elba (Beasts of No Nation) as the heroic Roland Deschain and Matthew McConaughey (Interstellar) as The Man in Black, a.k.a., Walter was a coup for the film.
As long as Roland is in the game, The Man in Black has reason to stay in it himself.