You are halfway through your project completion, but you now know that it will no longer serve its intended purpose.
You are left with two choices:
- Abandon the project and restart with what you can salvage from it, or
- Keep pouring your time in seeing it completed hoping that it will still work.
Most people will choose the latter, because it is painful to give up your incurred cost and hard work. Sunk cost is always painful, but a failed project will still fail at completion.
See the sign when you must quit, quit early, and reinvest your time into a better venture.