What event was directly responible for the dramatic increase in US healthcare costs?

The dramatic increase in U.S. healthcare costs can be largely attributed to the implementation of the Medicare and Medicaid programs in 1965. These programs expanded access to healthcare for millions of Americans, leading to higher demand for services and increased spending. Additionally, factors such as rising prices for medical services, advances in medical technology, and administrative costs have further contributed to the overall escalation in healthcare expenditures.