Marty's list of traits that enable someone to develop Product Sense: humility, curiosity, empathy, a genuine desire to talk to users and customers, and a sense of agency.
Humility is the cornerstone: "If you don't have humility, why would you bother spending your time talking to customers?" Without it there's no reason to seek out disconfirming evidence from users, and no motivation to keep learning once you've had some early success — see the dogma failure mode in Domain Knowledge Minus Domain Dogma (Hiring Against the Domain-Expertise Myth).
Development techniques Coaches build these traits deliberately rather than waiting for them to appear:
For a more intensive, immersive technique aimed specifically at building curiosity and empathy, see Customer Shadowing as a Product-Sense Technique.
Once someone has actually built these traits into real expertise, colleagues stop caring how they got there and judge only current competence — "humility only lasts a minute." See Trust-Building via Visible Learning.
An early, unearned success can be misread as proof of skill rather than what it actually was — in Christian Idiodi's account of a $26M failure, an earlier win he attributed to 'knowing nothing' and pure curiosity was later reinterpreted by himself as evidence of skill. The arrogance that followed — not the initial lack of knowledge — is what actually destroyed his judgment. Curiosity and humility are protective; the trap is letting a lucky outcome convert curiosity into unearned confidence.
Humility is framed as a transitional tool tied to the learning phase, not a permanent trait to display indefinitely: 'the humility... it only lasts the minute.' Once competence is achieved, the story of how it was acquired becomes irrelevant to others — 'people forget how you learn, they just care that you know.' The practical implication is that visible-learning techniques (see Trust-Building via Visible Learning) have a window of usefulness tied to the learning period itself, not a lasting reputational effect on their own.