My guess is that it all started by
1) The USA spending is/was much more than politicians dared to charge taxpayers
2) As a result there were deficits - large deficits
3) Therefore a lot of money had to come from somewhere to pay for all that spending.
4) Money was partly borrowed, and partly printed. Many customers in the USA are buying Asia-made goods and services; thus their money goes to Asia, and only a small portion(?) is coming back because people in Asia are not buying enough from the USA. Blame that for some of the problems.
5) That caused devaluation of the US dollar. Going back to Nixon's time, before Nixon, since 1944(?), the US dollar was pegged to gold at the rate of only $35 US dollars per ounce of gold. Compare with the price of gold now!
6) Therefore the debt instruments payable in US dollars held by lenders were/are worth less and less. And the US dollar reserves held by central banks in many countries similarly are now worth less. Confidence in the US dollar has been lost.
7) That caused the lenders to look for alternatives, to somehow limit their losses. I am not aware of any solution that may have been found so far.
8) The Special Drawing Rights (SDRs) are a "basket" of currencies, with, as I remember it from some years ago, it may have changed since, the US dollar being weighted prominently. Therefore probably the SDRs are considerably dependent on the US dollar and therefore may not be a good enough substitute for the US dollar unless, maybe, the weightings are revised, and other currencies added into the 'basket".
9) If and when interest rates will rise, stand by for additional problems/troubles/misery. And will current holders of US dollars want to sell their US dollar holdings? That would likely further devalue the US dollar.
10) Good luck to all of us - we may need the best of luck we can get!