That's not an accepted definition anymore. An increase in the money supply is just that - an increase in the money supply. Inflation is a measured increase in prices of a basket of goods. Those two are not the same thing - although the former can contribute to the latter. It does not have to, though, and certainly not 1:1. There's many reason prices go up: supply chain disruptions, for instance, and change in tastes/demand profile - or externalities like taxes, zoning and regulation. The idea that a supply increase alone represents inflation is a long-discarded Austrian economics principle.

In part because what you do with that money matters. Personal saving rates are near all-time highs, and velocity near all-time lows, meaning that new money? It's not actually moving through the economy and therefore not contributing to a secular increase in prices, or a reduction in purchasing power. This is why measurement matters. [1, 2]

The money supply wasn't increased to "mask" a contraction in the economy, it was done to avoid a deflationary spiral thereby preventing the economy from contracting further and allowing it to recover. The economy did in fact recover in part as a result of the influx of capital. You can see this in reduced unemployment rates and increased GDP in real dollar terms.

The money supply today is controlled via fractional reserve lending wherein a loan creates both new money in circulation and an obligation to repay that debt. That means all new money that's created is fully backed by demand for that same money. As that loan is repaid the money blinks out of existence. The Fed has the capability therefore to reduce the money supply by simply increasing interest rates. This in turn decreases demand for new loans, and causes a net reduction in outstanding supply as the existing loans are repaid.

What you're describing isn't a bet that an increase in the supply will lead to hyperinflation but rather a bet against the Fed's tool chest. That's not one I'd personally take, but to each their own.

What you saw in your [1] and [2] isn't an isolated increase in supply leading to massive inflation - after all, they'd just, you know stop - but rather political instability causing the population to reject the currency as I described in the post to which you responded. It's far more nuanced than you're making it out to be as you can see for yourself. The M2 supply doubled in 2020 but prices are up, what, 5% YoY - even after massive supply chain disruptions and tons of re-opening demand chasing limited supply? The M2 supply exploded after 2008 but inflation once again did not. The M2 supply is something like 30X now what it was in the 1970s but prices are 8X higher. Your model cannot account for this, and is such, it is broadly no longer accepted as it is obviously, observably incomplete.

> What will happen to the stocks (which most people on this site feel "protected" by owning) I don't even know.

You can research this, as there are countless examples in other world economies. Companies that provide necessities will continue to exist, as they do in Venezuela, and they will retain some value - or even grow in real dollar terms, depending on the industry. Some will collapse. Venezuela has a stock exchange, after all.

However, at the end of the day, it's incredibly, incredibly unlikely that hyperinflation will occur in any primary reserve currency anywhere in the world due to demand for that currency both at home and abroad. If it did, guns, ammo, canned food and potentially gold would the be the currency of choice. Requiring an internet connection and all the world's power and semiconductors to transact? Not so much, in a Mad Max-esque dystopia. You can't use Bitcoin in NK right? What makes you think you'd be able to use it in post-apocalyptic Kansas?

[1] https://fred.stlouisfed.org/series/PSAVERT

[2] https://fred.stlouisfed.org/series/M2V