Luke was just following his mentors when going gets rough you pick a planet to hide on away from the world just like Yoda and Obi-Wan. Luke has surpassed them as he did not pick a desert or a swamp to hide in he went with an actual nice location. The jedi are naturally cowards when things get rough they run they have proven this time after time. Basically they are hardcore failures who did not protect the universe and could not redeem themselves. At least Luke understood this and tried to end the jedi order knowing that they are useless and failures. Rey would be better off training elsewhere so she can become something better then a jedi something that actually matters.