Yes, you read that right, yes I’m talking about Buggy, and no I’m not joking.
Since his childhood as an apprentice on Roger’s ship, Buggy has been obsessed with finding treasure. While he loves riches, the treasure that Buggy seems to desire most is the one that belonged to Captain John, and he’s been seeking out this treasure for a long time.
Early in the story, we see Buggy and his crew searching a skull-shaped island for Captain John’s treasure. Buggy seemed very sure that this was the loot’s location, although he ended up being wrong.
Later on, Buggy was captured by the Marines and sent to Impel Down, after he ran into a marine garrison, in search of the treasure. As we know, Impel Down is where he ran into Luffy and gained the marker that leads to Captain John’s treasure. While it isn’t 100% confirmed that this is a legitimate treasure mark, it’s highly likely since it was taken from Thriller Bark, where Captain John’s zombie was.
So, what does this have to do with Laugh Tale, and how is Buggy the key to getting there? My theory is that Captain John’s treasure is the final (missing) Road Poneglyph.
Here’s why I think this…
Captain John was a member of the notorious Rocks’ Pirates. After the God Valley Incident, the Rocks’ crew disbanded and went their separate ways. Two of the crew members ended up with a Road Poneglyph, Big Mom who settled down in Tottoland, and Kaido who settled down in Wano. A third road poneglyph was located in Fishman Island, which was in Whitebeard’s territory, but it has been missing for 26 years.
In the recent Road to Laugh Tale chapter that Oda released, three potential locations for the missing Road Poneglyph are suggested, being Elbaf, Vira, and Fullalead. The one that piqued my interest was Fullalead Island.
Fullalead Island is where the Rocks’ Pirates first came together, so it makes sense that one of the former crew members (John) would return there after the crew disbanded. The island also has a massive stone skull on it, just like the island that Buggy was so sure was the location of Captain John’s treasure.
This would also explain why Buggy hasn’t yet acquired the treasure, since Blackbeard currently resides on Fullalead.
If Buggy and Luffy run into each other again, Buggy (who has a loose tongue) could let something slip about Fullalead island, which could lead to the Straw Hats going there and eventually finding the missing Poneglyph.
Basically, Buggy and Captain John’s treasure could be the setup for not only finding Laugh Tale, but also the seemingly inevitable clash between Luffy and Blackbeard.
Getting into some real-world history, one of the islands that Fullalead is based on, Port Royal, is considered one of the most important archeological sites in the world because of all of the ancient treasures and artifacts that were hidden there.
The pirate the Captain Jack may have been based on, Calico Jack, was executed on Port Royal.
Now I’m grasping for straws a bit here, but we know that Shanks has some unknown ulterior motives, and a lot of people have theorized lately that the pirate that Shanks told the Elders about was Buggy, which ultimately led to him becoming an Emperor.
Shanks knows about Buggy’s love for treasure, so he may have warned the Elders that Buggy was close to the last road poneglyph after realizing that Buggy had Captain John’s treasure marker.
TL;DR: Captain John’s treasure is the final Road Poneglyph, and it’s on Fullalead island.
Theory by Chriscftb97 (https://www.reddit.com/user/Chriscftb97)