What I touched on in my post agreeing to DG's excellent summary was the dramatically increasing health care costs in the States, which actually has been increased by the Obama Health Care plan, hence the Trump demand to look seriously at the reform policy.
You can read this great report on some of this complex issue:
https://www.thebalance.com/causes-of-rising-healthcare-costs-4064878and the explanation of the Reforms if you are studying it, as I have now briefly done:
https://www.healthcare-management-degree.net/faq/what-is-obama-care-healthcare-reform/but I particularly noted the following statement:
"In 2017, U.S. health care costs were $3.5 trillion. That makes health care one of the country's largest industries. It equals 17.9 percent of gross domestic product.This is for a population of 330 million
Now compare this against this statement about the UK's NHS (covering a population of 67 million):
"Total health spending in England was around £125 billion in 2017/18 and was expected to rise to over £127 billion by 2019/20, taking inflation into account.
In 2017/18 around £110 billion was spent on the NHS England budget. The rest was spent by the Department of Health on things like public health initiatives, education, training, and infrastructure (including IT and building new hospitals)."Without analysing these figures too closely, and not adding various factors like the Insurance companies involvement in the USA, you can see on the face of it the differences of scale!!
That is what Trump, or any other US President has to deal with when touching on their health care issue!