Did Luffy Really Say “When Do You Think People Die? When They Are Forgotten”?

No. The speech that asks when a person dies, runs through gunshots and disease and poisonous soup, and answers "when they are forgotten," is not Monkey D. Luffy's. It belongs to Dr. Hiriluk, the quack doctor of Drum Island, and it is one of the most misfiled lines in One Piece because of where the story chooses to repeat it.

The verdict

Misattributed. Wikiquote's One Piece page records the line in its Drum Island season under Hiriluk, in the compact form the dub gives it: a man dies when people forget him. The longer catechism, with its list of ways people do not die, is the same speech in the subtitle wording, and every source that gives it a scene gives it to Hiriluk, in the flashback where he explains himself to Chopper before walking to his own death. Luffy is not the speaker. He is not even in the flashback. The attribution to him comes from quote collections titled with his name that sweep up every memorable One Piece line, and from the fact that the speech is quoted again, much later, in a scene he is part of.

Whose line it is

Hiriluk is a fraud with a good heart, a doctor with no licence who believes a country can be cured, and the speech is his answer to the question of why a dying man keeps working. He is telling Chopper that the cure for his own death is to be remembered, and then he goes and dies in a way that guarantees it. The line's power depends entirely on the man saying it having weeks to live. Put in Luffy's mouth it becomes a slogan about legacy from a teenager who has not lost anyone yet; in Hiriluk's it is a will. Hiriluk's page on this site carries the compact version with its source, and it is the only One Piece entry here that belongs to a character who appears in a single arc, which tells you how much the speech outweighs the screen time.

How Luffy got the credit

Two mechanisms. The first is the usual one: quote sites organise by the famous face, and a "Luffy quotes" page will take the series' best line regardless of who said it, the same drift that put a Might Guy line under Naruto's name. The second is specific to this line. When Chopper remembers Hiriluk's words during the fight for Drum Island, and when the story returns to the idea of being forgotten in later arcs, Luffy is the character on screen, and a screenshot with a caption does not distinguish between a line being said and a line being remembered in someone's presence. The speech is Hiriluk's. The face on the image is often Luffy's. The caption follows the face.

What this site does with it

The Hiriluk entry quotes the dub's short form, because that is the wording a transcript records; the long catechism circulates in half a dozen translations and none of them is an official English text this site has seen. Luffy's own verified lines, about being King of the Pirates and about not wanting to conquer anything, are on his page, and the two invented Luffy lines this database has already caught, the one about forgetting being a wound and the film line about taking risks, are worth reading beside this one: the theme of memory keeps getting attached to him, and it keeps belonging to someone else.

How we checked

The verification process asks for a primary or editorial source, and Wikiquote's episode-numbered page supplies the speaker and the scene. Nothing attributes the speech to Luffy with a scene, because in no scene does he say it. The entry in the fact-check database is misattributed, and the rest of the series' verified lines are on the One Piece hub.