> ... If no one knows about it or won't give it a chance, then it's as if it never happened.

It is rational to stop somewhere between 0% and 100%. There is no guarantee you will find traction in the last 10% or the last 1%, if you get that far. It might have been rational to stop at 17% and instead spent the time and resources on something else.

To make an honest and rational decision, there should be go-conditions at several points along the project. Work stops when conditions aren't met.