A pirate-targeting thief in a pirate-saturated world makes no economic sense as
pure pragmatism (more pirates than civilians, harder targets, no payoff in
reputation, and being recognized by any pirate crew at sea is a death warrant
for a lone thief). The line plants the question: why pirates, specifically?
The answer, when it comes, is one of the foundational tragedies of East Blue —
Arlong occupies Nami’s home village; she has been buying it back
from him in 100M berry installments since childhood; the village mayor
Bell-mère (her foster mother) was murdered by Arlong; Nami’s
only path to freeing the village is stealing exclusively from pirates because
the village is a pirate-occupied zone and the ransom is denominated in pirate
treasure.
This makes the Ch 8 line a textbook dialogue-as-character-disguise beat:
the character is presenting her motive as cynicism to keep new acquaintances
(here, Luffy) from probing the true reason.
Technique stack
name-etymology — nami (波) = “wave”. Her navigator role and her sea-as-prison
backstory are both pre-coded in the name.
dialogue-tell — the specificity of “only pirates” is the tell.
character-introduction — Oda’s pattern of introducing Straw Hats with a moral
surface trait (Zoro: man of his word; Nami: only-pirates thief; Sanji: feeds
the starving; Robin: child who survived; Brook: keeps promises after death)
whose origin is the arc-defining tragedy.
Earliest known caller
(Not researched — the Arlong backstory is famously a Reddit-era anchor point,
but the Ch 8 line was identified as a setup beat early in the manga’s run.)
Ch. 69 — code inverted by Officer-Nami reveal
Ch. 70 partial-payoff
The Ch. 8 “I rob pirates” code is sourced: Nami robs pirates as the operational mechanism for the Arlong ransom. The thief-not-pirate moral self-distinction (Ch. 10, 20) was the internal moral cover-story for stealing pirate-treasure to buy back her village from a pirate. The chapter is the axis-inversion of the code.