It sounds like you are saying, "Don't worry, if we can't manage to pay back the loans we have taken against the planet's nonrenewable or slowly-renewing resources, we can just declare bankruptcy and start over", which is not as reassuring as you seem to imagine.

Bankruptcy works on a small scale, as an act of grace, because the bankrupt party can bootstrap themselves back into productivity using the functional economy around them.

When too many people go bankrupt at once, the economy crashes.

When the whole planet runs out of ecological credit, and we all go bankrupt at once, where are we going to find another civilization to bootstrap from?

All the easy energy is gone, forever. There will never be another coal- or oil-driven industrial revolution on planet Earth. If we reach bankruptcy on the scale of a planetary ecosystem, it will most likely be permanent, as far as Homo sapiens is concerned.

Whether bankruptcy is necessary to capitalism is irrelevant to your point

> You must have a way of paying the debt back, or you wouldn't have been able to obtain the resource you did on a promise.

I am stating that some people _don't_ have a way of paying the debt back, and yet they have been loaned to, incurring debt, and thus ruined (as the parent you were originally replying to suggests)