This is not accurate at all. Approximate costs can be estimated before hand. You can even ask the customer if they are willing to pay a specific amount for th

This is not accurate at all. Approximate costs can be estimated before hand. You can even ask the customer if they are willing to pay a specific amount for the feature. But, insisting you have to build and deploy a feature first, before you have any idea of its impact, that is, an expensive, and foolish way to learn.