A really interesting discussion I've been seeing recently is about Usagi and how she is privileged in her world/story and how her selfishness plays into her character so I thought I could chime in!!
I definitely agree with the privileged piece of her character, she is not only a princess in her past life (which comes with inherent like physical privilege) but also has many friends who always protect her to the best of their ability and are shown on several occasions to be willing to die for her. Despite the tragic end to her life as Princess Serentiy her life after reincarnation is full of love, she has a family who cares for her dearly and before we meet her in the story she has tons of friends, then she meets the other girls and becomes close to them and also has Mamoru. All of these people care for her deeply and she has never lacked love in her life. Especially when you contrast this with other characters who are shown to live lonely, isolated lives before being brought into Usagi's inner circle. (This is shown really well in the R movie where the inner guardians and Mamoru all explicitly state that they were sad and lonely before they met her). Mako lost her parents to a plane crash, Rei's mother died of a sickness, Hotaru's mom died in a fire that left Hotaru mutilated and on top of that her dad put an evil egg inside of her, Mamoru loses his parents and memories, Setsuna guards the time gate alone, etc. Usagi has a good life as Usagi Tsukino before all of the Sailor Moon stuff starts happening (And after too but obviously my girl suffers more during that), she had a good life as Serenity even though she felt stifled on the moon and even though the fall of the moon kingdom and Endymion dying was obviously very traumatic for her, and she is shown a really nice future where she has a husband, child, and all of her friends surrounding her. All of this being something most of the other characters don't have, or at least not entirely.
As for the selfish piece I don't completely agree with it. Not that it isn't a true, but I think it's something her character does get over within the story. One of the biggest reasons she can be read as selfish is that she has friends that are willing to die for her time and time again, and the system that was set up in Silver Millenium has her being guarded by the inner senshi. Another point is her suicide after Endimiyon dies and when Mamoru is possessed during the first act of the manga. I think Usagi is a selfish character, but in the way that all she wants is for all of the fighting and violence to be over so that she can just continue hanging out with her friends. One thing that bugs me is people saying that she is selfish because the inner senshi are her guardians, because she didn't choose that. I feel like Usagi is always around during pretty much every fight and on the rest of the girl's levels until we get to like a big important fight and then everyone is prioritizing protecting her. I would have liked in the story for her to challenge that system where she is more important than her friends, like an episode/arc where she made it clear to them that she is not someone held above them in status but an equal.
Like tell me if this is an out there take but I think her suicide as princess Serenity really wasn't that selfish. She didn't have much power to fight and try and save her kingdom (she def could have tried but I don't think she would have done much) she didn't even have the silver crystal because Queen Serenity was using it, she lost Endymion and she got swept up in everything happening and took her life. Now this made it more difficult for Queen Serenity to fight off Queen Metalia and might have cost the moon kingdom it's life, but I don't think it was particularly selfish of her at all. However, I think her suicide when Mamoru was possessed was kind of selfish (I'm sorry if that sounds bad) Like she could have tried to fight Queen Metalia with the Silver Crystal, things weren't so dire yet but instead she threw her life away because she couldn't bear it anymore. (I mean it worked out in the end but still she couldn't have known that). She knew the Silver Crystal was virtually the only way she could defeat Queen Metalia, that she was the only person who could actually use it, and that it was the world's only option, but she still chose to kill herself. And while she does get grace in the end, she is a 14-year-old girl in a really difficult and overwhelming situation it still reads selfishly to me.
But I feel like within the story we see her overcome her selfishness. I think the best example for this would be how she handles Mamoru being brainwashed in the first arc versus how she takes all of her friends being killed in the final arc. In the final leg of the manga, she loses everyone dear to her (All of the sailor guardians, Mamoru, Chibiusa, her future etc.) but instead of just rolling over and letting Galaxia and Chaos have their way she fights until the end. She is under the impression her friends are gone forever once the big spiky thing with all of the Sailor Crystal in it (sorry I forget what it was called) is thrown into the galaxy cauldron and she doesn't just admit defeat she decides to fight for the galaxy. She would NOT have done this in the beginning, but now she is prioritizing the universe over herself despite the immense grief she is feeling.
One more thing before I finally stop talking is a point I have seen a few times recently where people are mentioning how Usagi never really sees true loss. This is something that has always bothered me because like not once have we had a character close to Usagi die permanently (Correct me if I'm wrong obv but like at least all of her friends are just auto brought back to life) She never has to face real consequences for anything really. But I feel like that's where Sailor Cosmos comes in. She is a version of Usagi that has experienced this real loss and she feels hopeless. She is fighting something she cannot win because there is no end to it, and she has none of the people she used to love and rely on. Tying back into the selfishness piece, she comes back in time to compel Usagi to destroy the Galaxy Cauldron and all of life as they know it because she can't stand the fighting anymore. Now there is a little more to it than that, but I don't feel like I am misrepresenting the situation either. She now has seen loss where she can't just magically bring everyone and everything back to normal and she doesn't know how to deal with it, so she goes back to Usagi who also thinks she has lost everything and asks her to end it. But instead of taking the easy way out like she has done in the past she picks a solution that will end poorly for herself (If Sailor Cosmos is any indication) and saves the world instead. Other than the glimpse we get of Sailor Cosmos and her life we never really see Usagi lose anything in the entire manga, not permanently at least, and I think this plays back into the privilege her character has throughout the story. But her choice to protect the universe over her own comfort is another way she overcomes the selfishness that she has at the beginning of the story.
Anyways that's what I think about that. I feel like that was a lot of words for me to say that Usagi usually gets what she wants and because of that she is a selfish character, but as the story progresses and she gets more experiences her own harsh realities like losing her friends over and over again and facing an eternity of fighting for the universe as Sailor Cosmos, she overcomes that and becomes a less selfish more understanding character :) I would love to hear what other people think about this, I hope I worded everything in a way that made sense and sounded like what I was trying to say.