Jonathan Gruber opens MIT's Public Finance and Public Policy course's health care unit by laying out why health spending dominates government budgets, framing it as the single largest expenditure for most federal governments. Drawing on his own background in health economics and policy design, Gruber works through the basic economics of health insurance markets, including adverse selection and moral hazard, and why these market failures justify government intervention. The seventy-eight minute session sets up the analytical tools students will use in later lectures to evaluate specific programs like Medicare and Medicaid. Delivered as a standard classroom lecture with slides and direct student interaction, it is part of MIT OpenCourseWare's 14.41 course from Fall 2024, offered under a Creative Commons license. The talk stays close to core public finance concepts rather than partisan debate, building toward the empirical questions the course tackles in subsequent health care lectures.