It's a long story, and my entry point into understanding the breakup of the British sterling system was history about post-WWI shift from colonial empires to Harry Truman "development" (really maldevelopment, the language used for capitalist NGO aid today is very similar to his inaugural address).

Long story short it involves merciless application of death and torture to enclose a region and keep costs down, as well as ruthless exploitation of civilians to try to crack guerillas, the Phoenix Program's main innovation over what was implemented in the Congo and Malaysia was a proto-internet communications system,and a methodical operations system escalating above that to commando squads and air strikes. The philosophy of anti-colonial torture has only grown more severe and incorporated electrical wires, clinical psychology, and evasion of human rights organizations. Look up "The Five Techniques".

This is in order to establish a top-down system where colonies do not trade with one another, but only interface with the rigged colonial economy. Wall st + world bank + imf system has just taken this to further extremes with Blackrock and Vanguard against 84% of the population of the world plus 90% of the population of the remaining 16% in global north countries. The currency system being used is less crude and there is also the technological dependency on the payment systems like Swift to consider.