'He' (the US) owe it in large part to the world, who were forced to buy us debt in order to buy oil. China is the biggest holder of US debt iirc.
The US's voluntary withdrawal from the post ww2 economic order (from which it profited greatly) has absolutely hastened and cemented this process.
This debt is coming due, the strength of the dollar has already dropped greatly, US interest rates will rise. The US dollar will be cheap enough to compete with India and China to be the world's factory (a major part of Trump's election campaign and success).
It won't happen all at once as the world will look to manage America's decline while trying to maintain as stable a transition as possible.
But please be aware, this debt is going to come due and it has absolutely been hastened by Americans voting for Trump a second time. Fore warned is forearmed. Good luck.
An office-friendly version of this would greatly improve my well-being so productivity at work.