Says the man midway through a 40-story fall from a skyscraper: "So far so good!"

The alternative is a static or deflationary currency. This leads to hoarding of assets which were originally intended to serve and increase commerce. Think Bitcoin. Without MMT, we would be falling from a skyscraper as you depict.

Bitcoin isn't static or deflationary. There is a schedule of inflation built in via the mining reward which is currently at 1.5% until the next "halvening" where it will become 0.75%. The mining reward will continue to half every 4 years until roughly near the year 2140.

https://charts.woobull.com/bitcoin-inflation/

You realize 2140 isn't that far away and that the cap is what is inflating current values (and coin hoarding) right? Just ask investors and they will tell you.

' deflationary currency ... leads to hoarding of assets '.

Someone owns every asset. By making it impractical to save using the fiat money, savings goes to non-fiat items like land, stocks, energy, and BTC. This harms the poor who are rarely able to escape into those non-money items.

Every fiat currency is different. Many poor in Argentina would argue that the USD, obviously inflationary, is a good store of value.