Stated vs Revealed Preference
Stated preference is corrupted signal. Revealed preference is what someone actually did when they thought no one was measuring. If you can't construct one before you build, you're stalling.
The entire customer-discovery stack rests on a corrupted source: what people say they'll do. Stated preference and actual purchase behavior have notoriously low causal correlation. The polite answer, the aspirational answer, and the "I want to be the kind of person who buys this" answer all dominate the honest answer in any interview.
Revealed preference is the corrective. What did the person actually do — last week, last month, in a context they didn't know was being measured? A waitlist deposit is revealed preference. A LOI signed before you've built the thing is revealed preference. A click on a "buy now" button on a landing page for a product that doesn't yet exist is revealed preference.
If you can't construct a revealed-preference signal before you build, you're not validating, you're stalling.