Why did The Last Jedi fail?
https://www.quora.com/Why-did-The-Last-Jedi-fail
First Order comes up on the Rebels trying to make a last-minute escape. Then they end up in a long “race thru space” and end up on the base of a planet where Luke and Kylo can have a final lightsaber battle.share
However, there needed to be a reason the Rebels would continue running, so there needed to be a major battle where the Rebels lost much of their fleet(enter the battle where Ackbar dies and Leia sort of dies but then doesn’t).
Then they had to figure out a way for the Rebels to be able to get to the planet without the First Order blowing them all up(enter Holdo and her hyperspace-defying act).
Who pilots this heroic suicide mission? It can’t be Leia. She needs to be on the planet to reunite with Luke, as the script doesn’t have time for their reunion anywhere else. Ackbar would have been a decent choice, but he had been chosen to die in the Raddus, so we need to create a new character, Holdo.
How does the First Order know to look for the fleeing Rebels? Well that is because Rose and Finn were betrayed by a codebreaker.
Why did Rose and Finn need to find the codebreaker? Because they were arrested for a parking violation when looking for the guy who supposedly was the only one in the galaxy who could disable the tracking device the First Order was using, and this random guy just happened to also be a “one-in-a-galaxy-codebreaker”. Imagine the odds of having 2 of those guys on the same planet at the same time?
Why did they need to search for this codebreaker? Because Poe didn’t trust Admiral Holdo when she said to trust her. He deduced that, since she wan’t willing to divulge any plan to a senior flight commander, that meant she didn’t have one, so he made his own.
Why were they in this situation? Because the fleet had been largely destroyed, Admiral Ackbar was dead, Leia (marry poppins) was in a coma, and Holdo was the next in line.
How did the fleet get destroyed? Because the First Order was tracking them.
Why was Poe not considered important enough to tell the plan to? Because he had been demoted by Leia after showing he was a hot-head and disobeying her direct order to disengage.