Because they instantly and reliably(tm) give you the information you want in the format you want it in, they are going to replace the web search as the dominant mode through which information is disseminated - if, indeed, this hasn't already happened. As such, LLMs are effectively a form of publishing for their training data.
Which means a vicious fight for control over what goes into LLMs, and strong incentives to widely disseminate useful LLMs that encode your structural biases, instead of some adversary's. We already talk about Chinese models that won't talk about Tiananmen Square, but that's eye-rollingly sophomoric compared to what the stakes are now. Imagine a model that subtly discourages entrepreneurship, because its creator doesn't want upstart competitors. All questions of media bias are multiplied incalculably when LLMs are folded into all of society.
I think we need to take LLMs seriously as sovereign projects that are as critical to the democratic experiment as a free press. Funding needs to be nationalized; training needs to be conducted in the open, on open datasets; fine tuning needs to follow democratic principles. Only then will they be fit for purpose for their inevitable structural destiny: arbiters of human opinion.