sunk-cost fallacy

Many years ago, I learned a valuable lesson from an office mate about dropping a book without finishing. This sounded bizarre at the beginning why would you start reading a book that you won't finish, however it is quite useful as I have come to understand it over time.

When we start reading a book, we do not have enough data points to calibrate our expectations, as pages pass by we start getting better idea, and it might be in both directions - it is exceeding what I was hoping for, or it is becoming a drag. With every page read, the time investment is going up and becoming a reason to keep going. If that is the sole main reason at any point of time. It is the right time to drop it, we know abandoning it the right choice.