Comment by aeonfox

I've fallen for this trap a few times before. It's a collision of pareto principle and nirvana fallacy. Diminishing returns dominate the last 20%, causing burnout, and you're held in the tension between sunk cost fallacy and perfectionism. The former turning burning ambition into an anchor around one's neck, and the latter slowly decimating any hope of release with perpetual scope creep.

The best strategy to avert this the next time around is to vastly undershoot on goal size. The scope creep will still happen because we can't change our nature, but the project has a much better chance of reaching completion.