I'm not that invested in the story, personally i think it's going to end in a train-wreck. Now naruto, i was invested in that, and wasn't going to stop reading until i got the pay off of naruto becoming hokage.
That sounds exactly like there is personal frustration involved.
Naruto is exactly the opposite of One Piece, it is a story that places politically on the right wing spectrum. It is about a boy trying to become the military dictator of his village, which he achieves thanks to his superior Gene pool.
The main character doesn't fix the problems of society, rather everything returns to how it used to be after an external (and in this case literally alien) threat is finished.
One Piece is exactly the opposite of that. It is about the main character becoming the most free man in the world. While giving a damn about political correctness, One Piece is highly progressive and meant to educate you in such a fashion.
I could imagine that not sitting well with Naruto fans, because after all that Manga is about uniformity and eugenics.
However I think many people unable to see this will be disappointed by One Piece in general.
Because while Naruto only shoe-horned in the prophecy and alien threat at the end, so you could get the typical right wing "End is well, all is well" ending, One Piece has always likely included both.
Naruto only needed Kaguya as the external source of all problems, because otherwise the story would have needed to fix these problems, e. G. with Madara or Obito as the final villain.
On the other hand, after a year of research and reading One Piece for over 20 years, I am convinced that One Piece is some kind of crazy "anti-bible".
Dreams, treasure, lies, depression, food, racism, rivalry, health, kings, war, water, land, God, friendship, life, death, slavery, sex, family, hatred, children, loyalty, gender... The list of ethical topics that One Piece touches is very long, where other Shonen stop at never giving up and the power of friendship, Oda tries to educate you about something every single arc.
The Strawhats are idols and not saints, a large part of the meta-story (Chaoskampf) is pagan, and it is not about worshipping or following kings or prophets, but about becoming a "King".*
But yes, (part of) the One Piece is likely a prophecy about the return of Joyboy (=Luffy).
Also something in space is already inside One Piece (Birka on the moon), and if we go by basic symbolism, the "Celestial Dragon" in Tenryu
bito (=people) should be the Milky Way.
But fear not, despite superficial similarities, it won't be like Naruto at all. Luffy will always just be Luffy, but the world will be fixed and the end will certainly involve some kind of "enlightenment" or message, just like every substory of it does.
*used in a very broad context, but the Freest Man in the World, and the King of the World, are two sides of the same coin and Oda is already going that route with Im and Xebec, also I don't use this exclusive for Luffy but all the Strawhats instead.
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