Once you realize that the theme of this entire movie is "failure due to hubris" - Luke even says those exact words when taking about the Jedi Order, I think it all falls into place. Nearly every single character/group in The Last Jedi fails because of their own hubris. Everyone fails.
The Resistance has a small victory in the beginning of the movie but then they spend the rest of the time running away, and their ultimate escape plan fails because Holdo considers Poe "just another brash flyboy" and not worthy of being told the entirety of the plan.
Snoke fails because he underestimates Kylo Ren.
Rey fails because she overestimated her own chances to turn Kylo.
Luke failed Kylo.
In the end, most of the characters learn from their failures. This movie was literally about, as Kylo says, "destroying the past" and moving forward. It wipes the slate. Episode IX should be interesting.
Oh. Not nearly enough R2-D2.