The thing is, its gotta be something ridiculous to where even WB/Oden found it weird, almost childish. I love the "
Use One Piece to buy the world" idea, but it could only truly happen after:
- One becomes PK
- Liberates the world from the WG
Essentially, by giving the world enough wealth, disparity of control won't exist. Blackbeard is aiming to control the world via chaos/destruction. WG does it through coordinated control. Shanks may be trying to do the same through "transaction".
Its also why I think something is going on with Shanks. The idea of Luffy/Roger saying the same words was stated in a flashback by Rayleigh in chapter 506/507 from Shanks. I personally think that with Shanks' supposed allegiance or at least openess to discuss issues with the Gorosei, plus a mysterious motivation hinted in Oden's flashback, he has entirely misunderstood Luffy's and Roger's words.
This is purely a guess, but if its about buying the world, Shanks may be thinking Luffy is attempting to buy the world and establish peace with means to control it, not to free it as luffy intends. Its also why I think Shanks is heavily based on one of the most famous Yakuza, Shimizu Jirocho:
https://en.m.wikipedia.org/wiki/Shimizu_Jirocho. Read through this and you'll see how many similarities he has with Shanks, especially his ability to resolve conflicts without violence, yet at the same time, be extremely violent as a man. This is actually part of the reason why I think Shanks is the true leader of the Underworld. The goal of it is to gain enough cash to buy the world, along with some other goal Shanks has.
If people do not believe the Shanks connection to the Yakuza, here are some other points to consider:
- His bounty is a direct Yakuza and Oicho-Kabu reference (which is where the name Yakuza comes from). There are heavy gambling connotations with the bounty
- He "bet" his arm on Luffy. The Yakuza cut their pinky as either atonement or a bet when they have no money to give. We essentially do not know what the bet is.
- He is referred to as "Kashira", which is "boss" as in a mob boss, never "Taicho", which is standard for Captain. This has been established since Chapter 1. His crew has never called him Captain.
- His epithet, "Akagami" means "Red Haired", yes. But if you change the Kanji, it also means "Dirty God". Considering Shanks' messy and carefree personality, it sort of fits. It may also hint at him being the behind the scenes leader of the Underworld (it would also just officially tie that group to a major plotline outside of Doflamingo). Considering the WG also utilizes this network and openly talk to Shanks, it works in a way. This is entirely up Oda's alley, considering Raftel and Laugh Tale.
Basically:
- Blackbeard: control the world via chaos
- The WG: control the world by any means (war and slavery still exist under the WG, even if its not chaotic)
- Shanks: control the world via peace/buying the world. Owning it.
- Luffy/Roger: Free the world by buying it, via One Piece and the Final War. They dont want to own it however, the want to set it free.
Tldr: Becoming PK/Finding One Piece isn't the end all goal for Luffy, only part of it. Shanks knows this too, but is misunderstanding Luffy and Roger. This is why Shanks as a person is super enigmatic as a pirate and why we don't understand what he himself is trying to do in the long run.
Just something fun to think about