The 1920s featured political détente, debt liquidations by prior consumer price inflation, an introductory stalling of monetary inflation, a German economic miracle, and a broad-based technological revolution. The 2020s have none of these.
Different people often react quite differently to the same conditions, so attempts to blame religious conflict on material deprivation fail. Ideological differences also better explain why Islam is not monolithic.
The idea of ordinary people enjoying luxuries and "unnecessary" items has long troubled intellectuals and aristocrats. But thanks to capitalism, ordinary people can now enjoy the basic pleasures the ruling classes have long seized for their own.
The Japanese experience offers valuable lessons for the US and Europe. A loose monetary policy can stabilize a recession for the short term, but a persistent flood of cheap money paralyzes productivity gains and growth.