How high can we go before the system breaks?

Dunno, but the US GDP debt to GDP ratio is about 125%, and that of Japan has crested as high as 240%.

That doesn’t mean I think it’s a good idea, just that there are similarities (strong underlying economy, similar social structures, etc.) as well as differences - and Japan has managed not to fall into the abyss over this debt load. They haven’t exactly prospered, either, with a stagnant stock market for 20 years (more!) and a recent lack of innovation, at least so far as the comparison with Silicon Valley is concerned.

But: there’s not rioting in the streets, the grocery stores are full, people are still buying cars and homes and such. It would appear the limits of debt for modern countries is a kind of stretchy-thing, and we won’t know how much until it snaps.