I learned this the hard way with the social CRM I started in 2016 — I built for two years before I understood the customer well enough to charge them. The book’s chapter on market fit (Chapter 5) is the one I’d hand my younger self if I could.
Everything else is recoverable. You can change your pricing later. You can rebuild a feature. You can hire help. The one mistake that genuinely costs you years is building the wrong thing for too long, because you don’t get those years back.
If you’re going to read one chapter of the book and skip the rest, read that one.
