That 17% includes Net cost of health insurance. So that would go down a lot with the profit taken out of it. Also expenditures would go down with price regulation and the system would also generate money from licensed medicines. Also the simplified billing and administration of a single insurance system would save a ton of money. Especially since a lot of the overhead in hospitals is admin. This simplified billing would let doctors have private practices again.
You're dreaming. Commercial payer organizations have low profit margins, especially since the Affordable Care Act (Obamacare) instituted an 85% minimum medical loss ratio. Some of them already operate as non-profits. Eliminating them wouldn't free up nearly enough funding to make "Medicare for All" work with a mere 4% income tax increase. Do the math.
You appear to be confusing margins with absolute amounts. Eliminating all health insurance profits wouldn't be sufficient to close the gap on your "Medicare for All" proposal, not even close. I'm not necessarily opposed to a single payer system, but you need to do the math and be realistic about costs.
https://www.google.com/search?q=what+make+up+GDP+healthcare+...