Reproduced from the Economist, originally from Thomas Picketty's Capital in the Twenty-first Century
It is difficult to overstate the geopolitical impact of the destruction of European capital during the World Wars. Note that the graph here is capital as a share of national income. The European countries represented are now back to pre-war levels, and higher than the U.S., but it's the rate of capital loss (and the implied shock) that is most salient.
As with most things, America's narrative of its own success is more complicated than boosters or detractors would claim. One factor that absolutely helped the U.S. surpass its competition was that it is on a separate continent than its competition, so when wars broke out, they flattened each other twice in less than half a century, leaving the U.S. mainland unscathed. (Even Australia came in for worse treatment in the Second World War with repeated Japanese bombing runs on the mainland.) Probably because this was mostly the result of geopolitical good luck rather than any decisions America's leadership made, or America's cultural values or institutions, this part of the narrative is grossly under-emphasized.