Decimation Plague
One tenth of the world population dies as it mutates more in a larger population than in 1918, the virus moves much too fast by airliner for the vaccine production to ramp up for each strain, and the variants circle the world several times as new strains that are different enough from each other that your immune system doesn't recognise SARS I as having the same proteins as SARS II to XIII. It's equivalent to 1918's 2% times five different varieties.
1. Stock markets collapse. Not so much to the people dieing or being dissuaded from shopping, but to the lower supply of labor as so many workers die off, and the survivors are more in demand. It's a J-Curve thing. As workers die, the survivors are more in demand for filling their places, so they make more money, so they have enough money that some of their wives can stay home with the kids, which lowers the labor supply enough so they get another raise to retain them, so more wives stay home with the kids, etc. We go back to 1970's levels of working wives. Not to mention that we have to shut down 10% of the factories as demand drops. But it's wage increases more than demand drops that hammers stocks. The heirs selling the stocks doesn't just put selling pressure on the market, but also results in their leaving the job market temporarily to clean things up or live off their inheiritance.
2. House prices collapse. Lots of old people living alone in houses die, and their houses come on the market when their heirs inheirit and dump them. Lots of old people living alone in houses that survive move to apartments to save money as their stock market investments collapse.
3. Inflation. Bond market investments collapse. As wives stop working and leave the money economy their is less to tax. Sure, the people still working are making more money, but the collapse of asset prices reduces the taxes the rich pay by even more. We can't pay the national debt, more to the point we can't roll it over because the poor people aren't buying all that tax free municipal bonds and treasury bills. Not to mention that the heirs are not needing to work so much as they sell off their earlier than expected inheiritances and have a little fun.
