Like Mother, Like Son: The Downfall of Luke Skywalker in Star Wars = Rave 02-2018
Channel: H.H. Knight Reviews
Date: 23/02/2018

"Star Wars, Episode VIII: The Last Jedi" left many fans of the franchise upset and divided about the quality of the film, most notably the treatment of the iconic Luke Skywalker character. Mark Hamill, who has portrayed the character for decades, has also gone on record about his considerable apprehension about the change in direction of the role. I am among the fans that agree that the presentation of Luke Skywalker in the film was not consistent with the legacy of the character from the classic original film trilogy.  

However, I tried to think of a legitimate, in canon explanation of the character's radical change from a hero that had readily and repeatedly leapt into danger to save his friends, family, and galaxy into a disenfranchised hermit, quietly waiting for his life to expire. In terms of "in canon", I mean an action, storyline, character progression, and/or series of events that occurred in the theatrical releases of the Star Wars live-action films. No special editions. No deleted scenes. No obscure references from official comics, novels, interviews, cartoons, or video games. I wanted a theory based on clear evidence from the films.

I believe I found such an explanation. This video explains my fan theory. Enjoy.