Comment by pixelmonkey

k is widely used by a handful of big investment banks and big hedge funds for quant/finance stuff. There are only a handful of such companies in the world but they are extremely price insensitive, especially with regard to technology that lets them get a market edge. I suspect this is the dynamic that kx, the company, tapped into over the years. I also suspect this open source release is mainly because investment banks have come around on their desire for open source (rather than proprietary) software over the years, at least on some teams. You can see the open source release doc explicitly positions k vs Python, pandas, and polars.

For example, I have an old friend from a major investment bank who used to work on an internal (proprietary) pub/sub system but who, these days, works on integrations between that system and Apache Kafka.