"But you’re the Deep Thinker, so I guess you’ve detected some line toward unsustainability that the rest of us can’t grasp."
That's what you said. You've been telling me the debt doesn't matter for over a decade now. And as long as people view it as a binary choice between two parties, neither of which will solve the problem, see Simpson-Bowles, we are fucked. So the idea that there is only one threat to democracy is silly.
The way that democracy works, is that everyone gets a vote. I choose not to use mine on either horrible choice. A vote for Trump is a vote for January 6th, a vote for Biden is a vote for Chaz. But neither is a vote for setting the country back onto a sustainable path. Neither is a vote for a return to something resembling a functioning democracy.
Here's a small example of how we no longer function: a few years ago, the Senate passed a bill to eliminate daylight savings 100-0, the house didn't even take it up for a vote. Depending on the poll you look at, 80% of people want it changed. This is not a functioning democracy.