Destroy the gizmo, and the Resistance can zoom away and escape to fight another day. Daisy Ridley, who plays a young woman strong with The Force, seeks a Jedi master (Mark Hamill) who is in hiding and begs him to help with the fight against the First Order and maybe train her to be a Jedi - sounds a bit like 'The Empire Strikes Back' right? Why not, as 'The Force Awakens' was similar to 'A New Hope.' Then there is the puzzling and badly written (which fits right in with the rest of the movie which revels in its mediocrity and goofball jokes) subplot involving two Resistance fighters going to a casino to find a person who excels in hacking stuff so they can bring him back to the bad guys' main ship to sneak in unnoticed and destroy some gizmo that allows the bad dudes to track the Resistance fleet - what's left of it - even in hyperspace. The rebel Resistance are on the run, hunted down by the evil First Order ruled by the Dark Side.
'Star Wars: The Last Jedi' was a huge disappointment to a long time 'Star Wars' fan such as myself.