The problem with what you said is that it's a statistic lumping all households together. As such it's largely meaningless because it lumps Elon's household with some person living in a trailer park in Montana. They are unlikely to have similar disposable income.
Equally, while health care might represent 17.6% of GDP, this of course provides no limit on any one person or group. Indeed, assuming that most billionaires are not spending 17.6% one can assume the real cost to many I'd much (much) higher than that.
No to the parent's statement about "poorer". There are many things to measure here beyond just "cash in the bank". And there are terms like "middle class" and "majority" which are imprecise.
Nevertheless the point, as an anecdote stands. While America the country is rich, not all the people in it are. Indeed it seems to be increasingly split into rich and poor - the middle class is shrinking.
The good news though is two fold. Firstly most Americans seem happy with this setup (presumably because it maintains the illusion that they can obe day be rich.)
Secondly the majority of (not rich) people believe that having rich people in charge will benefit them. No doubt the incoming government of billionaires is something to look forward to.
Which is all yo say that each country gets what they want. The US _wants_ for-profit health care. They believe it is the best in the world. Other countries think its bonkers and have other approaches. That's perfectly OK.
Indeed this is democracy in action. We vote for people who will best do what we want them to do. Who guide us, not just by their words but their actions. We clearly understand the actions of the incoming guy (he's been there before). He's clearly pro-health-company (not pro health consumer) so this is (quite literally) what people want.
The future looks very bright indeed!