Roger, besides being Pirate King, was well known for the wealth he had accumulated. Prior to his death, he's questioned as to the whereabouts of his wealth⁽¹⁾ where he proceeds to gives a rather cryptic response, and it is this wealth that he accumulated that is the One Piece...
Just read up on about everything Gold Roger. Him and Luffy have so much in common. First Luffy and Roger made allies nearly everywhere they went: Skypiega, Water 7, Lougetown(Yes i know Roger was born there), etc.
The straw hat.
Just like all other D, they smile at death.
People also tend to...
Source: Chapter 2
One Piece is an object that no one besides the Gorosei know about in detail; it's well known that the general public and majority of Pirates do not have a clue as to what One Piece is⁽⁵⁰⁷⁾.
Doesn't it strike odd that One Piece is being sought for by all...
Lets say one piece series ends like 10~15 years later (or whenever oda feels like ending it)
Luffy finds one piece and becomes the pirate king
Who would win?
new pirate king luffy vs former pirate king gol d roger
note: I used dates b4 the timeskip
At the end of the skypeia we found about the existence of the second ancient weapon,
Poseidon, and later a note apparently from Gol D Roger saying "We came here, found the text and followed its guidance"...