These LLMs are incredibly smart compared to humans in some ways, but they're incredibly stupid in other ways. They're just another tool, and tools need users. Hopefully they will be another big force multiplier in knowledge based industries, but this will increase demand for knowledge workers, because they will become more valuable due to being more productive from having better tools.
If better knowledge tools reduced demand for the people using them, Moore's Law and the availability of ever more sophisticated software would have ravaged employment in the IT industry. But that's just not how that works.
It's based on the assumption that when a worker becomes more productive, that the only effect that has is reducing the amount of work there is for others to do, but that's an incredibly naive view. In fact it also dramatically reduces the cost of that work being done and increases the capacity of the organisation to do work. This increases demand for that work, it makes that labour more skilled, and increases profits thus stimulating investment. Yes there can be localised negative effects in some cases, sure. Ive seen some of those myself, but any economic realignment can have it's pains. Taking into account all the positives it increases the value of the economic activity overall.