Great Depressions like the one that hit in 1929 are very rare. They usually happen only after two great empires exhaust their finances. WWI involved two of the biggest industrial powers in a massive death-struggle that didn't destroy their industries but wrecked their currencies and beggared their workers. Russia was a major empire but a minor industrial power so when the workers there revolted, the loss of this sector's industrial base had much less impact than the collapse of Germany's currency and its huge war debts.
This chart is from one of my most dog-eared books, one of the greatest works explaining relative power and why empires collapse, 'The Rise And Fall Of The Great Powers' by Paul Kennedy. The chart shows how England, the leading nation in the world, supposedly the richest, spent the most money during that grinding, depressing stalemate of a war.
Germany spent $3.9 billion less than England. Inflation since 1913 has been ferocious. This probably would represent well over several trillion dollars in today's currency. Even today, no nation can take a financial hit that big and stay solvent. Europe's industrial production fell 30% and the US, fattened off of billions of dollars of loans to all parties in Europe, lived high and mighty during the 1920's. But with industrial production lagging, Europe spiralled downwards. The US cheerfully gave everyone more and more loans and the promise of being repaid was fantastic! Why, these were basically AAA subprime loans.
Then Germany couldn't pay and kept asking for better terms. This was OK with the US but not with bankrupt England or France. So they demanded full payments and Germany defaulted. This triggered the Great Depression. Even though the US was now the world's largest manufacturing power, our currency was mostly for home use so the British had to keep the pound strong. Trying to do this made things worse.
And so it is today: our empire won't retreat from its distant borders but these same borders are bankrupting us for we never recovered from the Vietnam War, we literally papered over the mess which remained and continues to poison our nation. The military/industrial complex is not making us rich, it is making us poorer. And the paper being laid over all this is the same paper the Germans used in 1924 to paper over their own bankruptcy: printed money.