Money is like stamina - you usually have much more than you think, but accessing it is not without a serious toll. Extreme example - you can probably sell an organ to cover your debt. And there is a wide spectrum of things you can do before reaching that point, many of them crossing the legal, ethical, and humane border.
The original BNPL creditors are not going to make you do them. They need to be legitimate, customer-facing businesses. But they can sell your debt to collection agencies, which will be more willing to put pressure on you. And if that doesn't work - there are always gray market collectors to sell it to.
This generation really is doomed - but not because of these words (or anything else it does, really)