The most consequential AI decision organizations face is not which model to use — it is whether to build AI capability or buy it. This article provides a principled framework for leaders navigating that decision, built around the distinction between commodity AI (which should usually be bought) and strategic AI (which should usually be built or owned). It covers three-year cost comparison thinking, vendor dependency risk, the hybrid architecture that works in practice, governance and regulatory considerations, and the long-term compounding advantage that comes from owning the right capabilities at the right time. Written for senior executives who need to make this decision with clarity rather than urgency.