This is a well-studied field, but you're right to question the underlying assumptions. This paper models human capital, future investment and national security [1], this paper [2] talks about the complementarity of consumption and national defense. This book starts out with the same assumptions I am making, but I can't speak to its overall conclusions bc I haven't read it [3]. More accessible article https://www.industryweek.com/finance/software-systems/articl...