The recognition that the development of a solution really cannot be profitable is very hard for the person who studied it.
Sometimes, the defense of this viability is done as a matter of life or death.
There are so many hours, effort and personal expectative when you are doing it and your ego does not let you to think in the failure of this initiative. On the other hand the creation of higher expectations can be bad. This should be avoided.
If business case is well prepared and the answer is “… no this solution is not viable for us!”. No problem, this is a valid answer and you are taking a good decision for your company.
This has to be explained during early phase of the analysis to avoid future frustrations.