Richardson cheerily relates the circumstances of the Market Crash of 1929. Krugman, meanwhile, looks at the situation from today forwards.
The three things Krugman looks at are a possible stagflation cycle, a liquidity trap caused by the bursting of the AI bubble and a debt crisis. All three are very, very bad.
The stagflation argument has to be linked - though Krugman doesn't do so explicitly - to rising energy costs. The Iran war has caused energy prices - and therefore the price of everything that requires oil to be produced or shipped - to spike, and as businesses begin to price this in, that can create rising prices, even as the economy does not grow. There is some evidence that we are seeing to productivity gains related to AI, but the real economy - as opposed to the stock market - does not seem to be growing at the same rate as prices are rising.
The liquidity trap is related to the AI situation, because if that's a bubble (and it sure seems to be) and it bursts, the US is not in a great position to escape the downturn with monetary stimulus, because interest rates are already fairly low. We could spend our way out, but that leads to the third risk, which is a debt crisis.
It seems unlikely that the US could enter a debt crisis - France might - because of the way the dollar functions. But the extraordinary costs of borrowing means that interest payments on US debt are rising at a time when we already have problems with revenues - Thank, Republicans! - and, oh, yeah, we are fighting a war with Iran.
Krugman also notes that there are risks we can't see. He talks about how Covid screwed everything up without warning, but what about a massive hack or crash of the digital world because of AI. That seems far more likely than SkyNet becoming self aware and wiping out humanity.
What goes unstated by Krugman, but Richardson nods at, perhaps without realizing the connection, is that we have absolute fucking morons running things in DC. Andrew Mellon's policies were a leading cause of the Great Depression, blinkered as he was by ideology. Trump is both blinkered and an idiot. The creatures he surrounds himself with warp themselves into his image.
If any of these risks become reality, we don't have anyone in the Executive branch who seems capable of pulling us out.
The market crash of 1929 didn't lead immediately to the "Great Depression." It led to one crisis, then another, most of which were met with poor or underwhelming responses. A depression was likely inevitable by the spring of 1929, but the Great Depression was created after October of '29.
Buckle up.