Comment by necovek

As with any attempt to become more precise (see software estimation, eg. Mythical Man Month), we've long argued that we are doing it for the side effects (like breaking problems down into smaller, incremental steps).

So when you know that you are spending €60k to directly benefit small number of your users, and understand that this potentially increases your maintenance burden with up to 10 customer issues a quarter requiring 1 bug fix a month, you will want to make sure you are extracting at least equal value in specified gains, and a lot more in unspecified gains (eg. the fact that this serves your 2% of customers might mean that you'll open up to a market where this was a critical need and suddenly you grow by 25% with 22% [27/125] of your users making use of it).

You can plan for some of this, but ultimately when measuring, a lot of it will be throwing things at the wall to see what sticks according to some half-defined version of "success".

But really you conquer a market by having a deep understanding of a particular problem space, a grand vision of how to solve it, and then actually executing on both. Usually, it needs to be a problem you feel yourself to address it best!