Better now? (I've had my morning coffee)
Its really not that difficult to understand Luke's decision to isolate himself and as to why he feels the following the path of the Jedi was a flawed decision . Considering where he is now in relation to both the Skywalkers past and future , really ever since his father was inducted into the Jedi order, there really hasn't been much to be thankful for.
Imagine the impact the discovery that your actual Father was the most hated and deeply despised monster in the Galaxy had on Luke and then later when that secret is exposed to everyone . To have been lied to by your most trusted teachers, Ben and Yoda, so that you walked blindly into its shocking revelation . That has got to hurt almost as much as getting your hand cut off. And then to finally drag an admission from beyond the grave that it was mostly their failure with Anakin that led to the "problem" in the first place .
Its not good. But Luke still choose the Lightside, to trust and have faith by being a "true" Jedi.Only then, to make matters worse, to be rendered absolutely helpless by the Emperors Darkside powers , despite making the right choice by rejecting the Darkside. Its only his fathers intervention that saves him and even that act of redemption ultimately kills him.
So really one could say, from a certain point of view, as a teaching organization for Force users and as a benefit for the safety of the galaxy in general , that the Jedi order with their rather toothless, banal platitudes, directionless musing and wrong prophecies properly suck.
But going forward what then makes it even worse is Luke is made to suffer what must have been an even more terrible blow and bitter lesson.
By choosing following the exact same path, structure and teachings of the old Jedi he manages to replicate the exact same tragedy and failure. To loose all of it AGAIN ,both his academy and his nephew, the son of his best friend and sister, to the temptations of the Darkside . When he ,Luke Skywalker, hero of the Republic and the Last Jedi, does not SEE IT coming despite being the son of Vader.
And at this stage in his life thats a crushing defeat. No wonder he walks away from all of it .
And thats why I don't have any problem at all believing in Luke taking the decision to isolate himself as he has. We've still no real information about whats really happened between ROTJ and TFA and I do think the ambiguity is being talked up in order to generate more interest in the story, but I have to say it does fit.
People have gone of the rails after suffering a far lesser personal misfortunes ,and lets face it, Lukes are galaxy sized. As the Wook put it in his posts, the guilt , self doubt and personal recriminations must be almost impossible to live with. He has not turned to the darkside but its darkness is smothering him in despair.
I know Mark was always going to struggle with this fate for his character. Its as bad and as unfortunate a road for Luke Skywalker to have had to travel as he or we could image. And it also runs so contrary to Marks own positive personality and ultimately as many of us here have commented here, the hopeful and happy future we felt Luke was promised at the end of ROTJ.
Spoilers; Interesting piece confirming being a Skywalker kind of sucks
https://www.youtube.com/watch?v=_F7OuhtzOB4