Irreversible individual life duration (T) constitutes the ultimate scarce resource in economic and social systems. Building upon the Life-Value Reflow Theory, this paper constructs a unified analytical framework centered on national-level time allocation. Individual lifetime is conceptualized as sequentially allocated among four activities: survival, structural extraction, reproduction, and surplus. The structural extraction rate (η) represents the system’s compulsory appropriation of individual life time. When η exceeds a critical threshold, reproduction time is mechanically compressed, triggering declining fertility rates, systemic vitality deterioration, and an endogenous “population-extraction spiral” toward collapse. Within this framework, three classic macroeconomic paradoxes—the Solow productivity paradox, the Easterlin happiness paradox, and Piketty’s inequality dynamics—can be uniformly interpreted as different projections of the structural extraction process under the absolute constraint of finite life time. Using 2022 OECD cross-country data, the paper constructs computable macro indicators that provide preliminary empirical support for the theory’s directional predictions. By formalizing the physical constraint of lifetime, this framework reveals that the contemporary collapse in fertility rates is not merely an exogenous cultural shift, but a deterministic structural consequence of systemic extraction compressing the intergenerational reproductive time window.