It's not sustainable. It's inherently an inflationary bubble of debt currency that will eventually hyperinflate and lose total. Then they will have to repudiate that currency and create a new one (probably CBDC.)

It's called Modern Economic Theory as in THEORY, hypothetical and unproven.

I personally believe that MMT is driven by the Marxist agenda to crater the US economy. So... it doesn't have to "work" or benefit anyone... all it is intended to do is put a professorial sheen on economic collapse.

All I see in MMT looking ahead is a void.