Countrys borrowing: where did it go wrong?

We have some countrys owing debts of such vast ammounts MANY smaller countrys would be so lucky to earn/spend a fraction of it.

My basic understanding of country to country borrowing is the interest vs. the good it will do for the countrys ecconomy.


I have a country on the brink of complex techonologys, but i need a large sum to make the research reality.
I borrow 1B of currency from country A, i invest im my research and create working experiments then develop export commodities. I sell them slow but surly and i chip away at my debt, hopfully faster than the debts interest collects.

So why oh why do we end up with extremly capable countrys owing such vast amounts to others. Time seems to make it worse.

Is it oversight from the borrowing countrys, is it too high of an interest.

Seems like some of the smaller countrys are forever in others debts, but how to change it.

Its not got better in many years.

So i ask.

Does the system work? (why does nearly every country has this sort of problem)

and

Where is it currently heading? (land transactions for debt right offs? technology or resource trades?)

As a young man to these problems, i seek those that have had their finger on the button for a while to step forward and help iron out any misconceptions and help with answers.

Thank you.