What was significant about the cost of the World War 2?

The cost of World War II was significant both in human and economic terms, with an estimated 70-85 million fatalities, including military personnel and civilians, which represented about 3-4% of the world's population at the time. Economically, the war led to unprecedented military expenditures, with the total costs estimated at over $4 trillion (equivalent to around $20 trillion today), drastically reshaping global economies and leading to post-war recovery efforts. The war also resulted in the destruction of infrastructure and cities, particularly in Europe and Asia, necessitating extensive rebuilding and contributing to the establishment of new international economic systems.