They built a better currency trade so people could buy what they want without plying redicious amounts of money. the bisnusses were not making enough money, the great depression started arround 1929 so the great depression would be a cause of there spending habbits.
The name for this idea is "Domino Effect" - this is a theory that says that if one country falls to Communism the neighboring countries would also fall to Communism, much like pieces of Dominos fall when a neighboring piece fell.
This theory was important in the Foreign politics of the US during the cold war.
