My two cofounders and I were in an Airbnb in Mountain View, Calif., rehearsing answers to common questions before our final Y Combinator interview. We had just had three consecutive months of 30 percent month-over-month growth, so we believed things were going really well. We went over the question, “How big can this business be?” I recited our simple answer, which was modeled based on how two YC alums encouraged us to answer this question:
This is a $10-billion market, and if we grow 25 percent month-over-month for the next three years, we’ll be a $1-billion company.
This answer is