Cost of healthcare for individuals is not a good metric to judge by. The ecosystem of hospitals, patients, doctors, insurers, health systems, and the federal government is complex and you're not going to get a clear picture of the overall impact of the ACA by looking as something as simple as cost savings.
One example, hospitals are required to treat patients whether or not they hold insurance. The hospital foots the bill for that care and it's a major reason why hospitals shut down (especially in underserved communities). Getting more people on insurance plans was a direct factor is keeping many struggling hospitals and health systems afloat.
https://www.statnews.com/2019/03/22/affordable-care-act-cont...
https://www.networkforphl.org/news-insights/the-affordable-c...
https://www.cbpp.org/research/health/chart-book-accomplishme...