The Great Depression did not reliably produce political violence across countries

Evidence

The chief problem with J-curve theory is the abundance of countercases. Consider, for example, the many countries in which the Great Depression of the 1930s did not increase political violence. Surely, the effects of sudden depression, following the orgiastic recovery of the 1920s were crucial—and no more in Germany than in all the countercases. — John T. Jost and Jim Sidanius, Political Psychology, 4355