I would add a layer beneath "Product/Market Fit" called "Seed Growth," and here's why:

Sean Ellis' Pyramid is awesome, but you'll never know that you have (or don't have) product/market fit unless someone is already using your product. But where do these people come from? For instance, Sean recommends sending questionnaires to your existing users asking them how disappointed they would be if your product was no longer available, as a way to determine if product/market fit has been achieved. However, this begs the question: where did those people come from who you sent the survey to?

This is where "Seed Growth" comes into play. You need to grow the initial user base, from nothing to something, before you can determine product/market fit and move on to the other levels of the pyramid.

There are a number of ways to find this initial growth, but I would recommend the relevant parts of Paul Graham's famous essay as a starting point: http://paulgraham.com/ds.html and I would recommend watching Growth Hacker TV (www.growthhacker.tv) as another source for growth tactics.

You can watch my episode with Sean Ellis here: https://www.growthhacker.tv/sean-ellis