"Every perception is to some degree an act of creation, and every act of memory is to some degree an act of imagination."
-- Gerald Edelman, Second Nature: Brain Science and Human Knowledge
5 The Capital War7 The Capital WarThe Capital WarChapter 7: US-China Relations and Wars2020-10-18Journal
As for the fundamental appeal of each of these currencies:
The dollar was discussed so I won’t repeat the picture.
The euro is a weakly structured currency made by countries that are tenuously held together by a currency union that is highly fragmented on most issues and economically and militarily weak.
The yen is a currency that is not widely used internationally by non-Japanese people and suffers from a lot of the same problems that the dollar does, including having too much debt that is increasing quickly and being monetized so that it is paying unattractive interest rates. And Japan is only a moderately powerful country, not a leading power in any important way.
The British pound is an anachronistically held currency that has relatively weak fundamentals, and the country is relatively weak in most of our measures of a country’s economic/geopolitical power.
Gold is held because it has worked the best for the longest time and, like the British pound, because it was held from a past time—i.e., before 1971 when gold was at the foundation of the world’s currency system. It has appeal because it doesn’t have the previously described weaknesses of the fiat currencies being overprinted. At the same time the size is limited because the gold market is limited in size.
The Chinese RMB is the only currency to be chosen as a reserve currency because of its fundamentals—China has the largest share of world trade, its economy is roughly tied for the biggest, it has managed its currency to be relatively stable against other currencies and goods and services prices, and its reserves and its other strengths are large. Also, it doesn’t have the 0% interest rate, negative real interest rate, and the printing and monetization of debt problem though it does have a lot of domestic debt that has to be restructured. Its drawbacks are that it is not widely used, it doesn’t allow the free flowing of capital and a free-floating exchange rate, its capital markets and its financial center have to be better developed, its clearing system is undeveloped, and it has yet to build world investors’ trust.