That's my fourth point above, viz:
The US stepping in as the world's leading manufacturer in the post-war era, having its industrial plant intact, raw materials available, and demobilisation providing for a vast increase in the labour force itself without wage reductions.The irony is that the countries which did substantially see their industry wrecked and received Marshall Plan or equivalent funds afterward turned into the most competitive post-war economies, most notably Germany and Japan.
The US managed to build out new infrastructure, where it couldn't convert its war plant directly (which in automobiles, lorries, locomotives, ships, and aircraft it largely did).
We saw spectacular greenfields development most especially in high-speed rail, first in Japan, then France and Germany, all of which saw both infrastructure and real estate valuations (the key obstruction to railroad rights-of-way) collapse after the War. (China's HSR build-out follows a similar dynamic, though with different reasons, as that country industrialised for the first time.)
(Edit: The US hasn't established HSR, largely I feel because its previously-transport-enabled real-estate became too valuable. It's not tractably feasible to buy rights of way in the US, alternatives such as subway construction are themselves phenomenally expensive.)
I'm not sure of all the reasons for the UK's relative economic stagnation, though I suspect it was a mix of WWI and WWII debt, not having its industry blown to splinters, being out-competed by the US, and losing its cheap inputs as the Empire collapsed and colonies were spun out as independent states.
(Edit: The UK didn't see an economic turn-around until the 1980s, largely as North Sea oil came online, a boom it managed to extend with financialisation of the City of London, though that was largely restricted to the London metro region itself at a cost to the rest of the country which is immensely backwards.)
It's interesting to note that the US's post-war boom began slowing in the 1970s (for reasons which are widely, and I strongly suspect mostly wrongly speculated upon, particular the goldbugs' hypothesis), whilst Japan and later South Korea's were just hotting up (the latter imploded with the asset bubble collapse in 1990), and later of course China starting to grow significantly during the 1990s.
But at the end of WWII, the US had huge productive capacity, largely non-obsolete factories, worldwide markets for goods, raw materials, and a largely intact workforce (vanishingly few overall war casualties), a situation few other countries could claim, and none at similar scale. This provided about two-to-three decades runtime before factors caught up with it.
And in light of the 1929 crash, helped both prolong the expansion out of that crisis and see that the rewards were widely distributed among socioeconomic classes rather than concentrated amongst the very wealthy. That formula's not been tried since.
(Edits: Note two late adds above, they clarify/expand my argument slightly, pre-empt some possible counterarguments, and shouldn't change the meaning significantly.)