"If printing money is harmless; indeed, why have taxes at all, and indeed, why claim "we can't afford" anything - whether a new highway, guaranteed income for non-workers, free healthcare including treatments and medication regardless of cost; and so on."
As I said, taxation drives the demand for the currency the issuer can create on demand, making it possible for governments to provision themselves without needing a revenue stream.
You'll never hear me claim we can't "afford" anything that benefits society. That is because a sovereign currency issuer can afford anything that is denominated in its currency. Of course, the upper limit to spending is always inflation, which can be mitigated by less spending or higher taxation.
The most common measure of our economy is employment. Fiscal policy should always be directed to full employment and the best way to do that is to put it on autopilot with a federally guaranteed job program. As the business cycles fluctuate, the program would also, but countercyclically.
This would eliminate the need for monetary policy as the primary tool to control the economy and stabilize lending rates. It would provide a more humane way of dealing with unemployment, set a floor for wages and benefits in the private sector, take most pressure off states to provide for the workers when business fails to and safeguard vital supply chains.
"But I think Ludwig Von Mises was right, endless expansion of the money supply will ultimately cause total collapse of the entire system of monetary exchange."
A fiat currency cannot have a "value" beyond its utility as a unit of measure for our commerce. It measures the value of resources and labor just as inches measure distance. It is the relative availability of those resources and labor that determine their value, not the "pricing unit" that denominates it.
As the monopoly issuer of currency, the issuing government becomes the price setter for its purchases. If government is not capable of restraint when needed then inflation is likely, but it is also mandated to provide sufficient currency to promote the "general welfare" and to fund growing population and the desire of the people to net save in its currency.
Clawing back all payments made to the private sector via taxation is essentially theft and provides no means to retire bank debt or net save as a store of value.
Can flooding an economy with currency cause inflation? Of course, but only after the potential for utilizing available resources and labor are reached. Up to that point, business will always increase production before raising prices in a competitive environment. This is the argument against the misuse of patents and monopolies.
"The WEF people are already saying, explicitly, "you vill not own property, and you vill be happy vith that". "
I'd have to see a reference/link to speak to that in proper context. I'm certainly the wrong pick if you're expecting a defense of the current powers around the world and their agendas.