Product-market fit gets talked about like a moment — a threshold you cross, a milestone you announce, a before and an after. That framing is comforting and wrong, and it produces a specific failure: teams that "achieve PMF," declare victory, and stop doing the thing that produced it.
Fit is not an event. It is an operational condition — a state the business is in right now, that it can have more or less of, and that it can fall out of without warning. The market that fit you last year is not the market you face today; fit decays as competitors move, expectations rise, and the early adopters who forgave everything are replaced by mainstream users who forgive nothing. PMF is something you are continuously in, not something you reached.
This is also why a single metric never captures it. A number crossing a threshold can mean fit, or it can mean a good quarter, a strong channel, a cohort that flatters the average. Feedback gets treated as evidence when it is mostly noise — what users say in a survey is a poor predictor of what they do under their own constraints with their own money. The signal that matters is behavioral and repeated: do the right users keep coming back, keep paying, keep pulling the product deeper into their work, without being pushed.
The technical version is its own trap: a system that works for the demo and a market that wants it are two different fits, and confusing technical PMF with business PMF can kill a company that has exactly one of them. The useful question is never "did we get PMF." It is "are we still in it, for whom, and how would we know if we were sliding out."