Healthcare spending is 17% of GDP.
We could take every tax dollar we collect now and still not have enough to pay for healthcare.
Plus we'd end up with about 30% of our GDP going to just the feds. Add in state spending and over 50% of the money in the country would be going to government.
We would turn into Europe in a decade. (Low economic growth, low income growth, high unemployment etc etc)
You're assuming that we'd be paying the same amount. The UK, by comparison, pays 7.7% of GDP towards healthcare. It is certainly not a perfect system (as the OP makes clear, wait times for non-life threatening surgery and for the elderly are much too long). The question is, though, is our system twice as good as Britain's?
The US is not ready socially, politically, or structurally for single-payer health care, but there needs to be some reining in of costs. The problem with a purely free-market system is that there is infinite demand. People will pay everything they have to stay alive, as it is better to stay alive with nothing than die with a fortune. This means that when a company has a monopoly on a medical technology or medicine (as provided by patents, for example), they can charge whatever they want. If a company found a cure for cancer right now, they'd charge hundreds of thousands of dollars a person until the patent ran out (they already charge tens for high end chemo drugs, which are crude poison compared to a real cure).
We can't get rid of patents, as it will remove the incentive to create these innovations in the first place, but there needs to be some balance between that incentive and the affordability of the treatment as a whole.