I’ve been wondering (and worrying) about this; I’m glad to get a plausible explanation for what’s going on.

The central, befuddling economic reality of the United States at the close of 2020 is that everything is terrible in the world, while everything is wonderful in the financial markets.

It’s a macabre spectacle. Asset prices keep reaching new, extraordinary highs, when around 3,000 people a day are dying of coronavirus and 800,000 people a week are filing new unemployment claims. Even an enthusiast of modern capitalism might wonder if something is deeply broken in how the economy works.

To better understand this strange mix of buoyant markets and economic despair, it’s worth turning to the data. As it happens, the numbers offer a coherent narrative about how the United States arrived at this point — one with lessons about how policy, markets and the economy intersect — and reveal the sharp disparity between the pandemic year’s haves and have-nots.

https://www.nytimes.com/2021/01/01/upshot/why-markets-boomed-2020.html