The author's main argument is that the relentless pursuit of efficiency paradoxically makes people feel more rushed and robs life of its richness. The author advocates for consciously incorporating 'beneficial wastefulness' (有益な無駄) — inefficient, non-productive activities — to regain mental well-being and a richer life experience. The correct answer accurately summarizes this point: society is losing richness due to efficiency, and intentionally having inefficient time is important. Wrong answer A presents the common belief that the author is refuting. Wrong answer B misinterprets the purpose of 'wasteful' activities; the author sees them as having intrinsic value, not just as tools to boost productivity. Wrong answer C is incorrect because the author's conclusion is a call to action for individuals ('自らの意思で「無駄」を慈しむ勇気を持つべき'), implying that individual change is meaningful.