It seems great until those imaginary numbers become worthless overnight.

Then you might have a bit of an "oh shit" moment as you realize that the industrial ecosystem required to substitute those imports would take a decade and a half to build even if your money were worth something, which it now isnt.

Lots of countries collapse due to overreliance on foreign imports. Argentina never recovered from its peak in the 1920s - it just kept bouncing from crisis to crisis. This is looking like an increasingly plausible outcome for the US.