Part 4 concludes The Architecture of Capital by examining when dependency stops looking cheap and optionality begins to carry a premium. Through Europe, the United States, China, and South Korea, it shows how capital architectures reveal their hidden liabilities under stress — and why strategic freedom depends on preserving alternatives before they are needed.

AI is not one industry but a layered system of energy, silicon, compute, connectivity, and models — and each layer requires a different form of capital. Part 3 of *The Architecture of Capital* examines why AI leadership depends not simply on how much capital a system has, but on whether its architecture can produce, regenerate, and sustain the right capital at the right duration.

European household savings flow through institutions, regulation, tax policy, market structure, and default settings to become productive capital for innovation, industry, infrastructure, and long-term growth.