How to tell if you’ve found true product-market fit

As Hadley noted in a recent tweet, one big danger facing startup founders is the premature belief that you’ve found product-market fit.

Understanding that idea is critical for startup success, so it’s worth revisiting Marc Andreessen’s 15-year-old post, in which he defined PMF as “being in a good market with a product that can satisfy that market” and claimed that founders “can always feel when product/market fit isn’t happening.”

So how can someone be wrong about finding product-market fit?