“Confronting fear is the destiny of a Jedi.” And her fear, as very clearly stated in the film, is that she will fall to the Dark Side; not that she will fail to save her friends.
Jar Jar, I don’t disagree that “wanting to protect her friends” could have been a good angle to take the film - in fact, I wouldn’t be surprised to learn that the “Control the Fleet to save your friends” concept was taken from an earlier draft of the script with this in mind - but in the final version, it wasn’t developed at all. It’s like Finn’s “Rey, I never told you” bit…it’s part of a story element that didn’t make it into the final cut.
In my read of the film, I see a constant thread of Rey sort of “standing apart” from her friends. Not in the sense that it’s a deliberate choice on her part to protect them, but rather because she’s growing more distant. More isolated, more insular. The opening features Finn and Poe on their own mission, while Rey is focusing on her own training, which establishes the dynamic. You have the moment on Pasaana, when they start looking around together, and then Rey wanders off to take her Skype call with Kylo. The moment where she veers off course, without telling anyone where she’s going, because she senses Kylo approaching. When she’s standing in the corner of the ship after casting lightning, zoned out, until Finn comes to check on her. When she breaks away from rescuing Chewie to get the Dagger back. When she leaves them on the shore and takes the skimmer, recklessly ignoring Jannah’s warnings. Fleeing to Ahch-To without saying anything else to her friends. The entire finale has Rey in one spot, and Finn and Poe in another. There’s a motif in all of this; it happens in pretty much every scene.
The thing is, none of that is done to protect her friends, as you claim. On Pasaana, why didn’t she tell them, “We have to leave, now! Kylo is coming!” She just…wandered 100 feet away, as if that would hide them from Kylo? On Endor, she had no clue that Kylo would show up; “they didn’t have time to wait” because the film gave them an arbitrary 16 hour deadline until Doomsday. And on Ahch-To, she doesn’t mention her friends even once. She just said “I saw myself on the Sith Throne. I’m scared of my own powers. I’m going to hide here so that I can’t fall prey to the Dark Side.” She goes to Exegol to face Palpatine, not to protect her friends. (If she’s trying to keep them out of harm’s way, why does she provide them directions to get to the battle?) If you want to make an argument that she’s trying to protect her friends, you can; but there’s no evidence in the film that supports that beyond speculation and wild (re)interpretation.
Again, it’s a fine angle for a story, there’s just no buildup to it in this one. There is, however, buildup to her giving in to the Dark Side out of her own intrinsic, personal failings. My original point here was to point out how weird it is that the film spends so much time building up this “inner darkness” angle, only to swap over to a “protect my friends” direction at the eleventh hour. That’s just sloppy writing.
Of course, criticizing TROS for sloppy writing is like criticizing Star Trek for using too much techno-babble…