This article positions cost management as a first-class architectural control rather than a post-hoc optimisation exercise. In regulated environments, cost decisions directly constrain temporal truth, optionality, velocity, and compliance. The article explains why FinOps must prioritise predictability, authority, and value alignment over minimisation, and how poorly designed cost pressure undermines regulatory defensibility. By linking cost to long-term value creation and regulatory outcomes, it provides a principled framework for sustaining compliant, scalable data platforms.