By the beginning of 1933 American national income had fallen by a third. World trade in this year was less than a third of its 1929 level. Germany was particularly hard hit by the Stock Exchange crash and the subsequent depression. If industrial production in 1929 is taken as 100, by 1932 it was only 53. That statistic, and the failure of the workers' leaders to respond, led straight to the rise of Hitler.
Most people keep their money in banks.
If too many lose their money, the banks go bust. Over this period about 9,000 banks closed their doors in the States. The banks tried to hang on by ruthlessly foreclosing on mortgages, bankrupting swathes of American farmers, especially in the south-western states. As the banks went bust, most people who kept their money in them lost everything. And so on.