The idea that a GPT-n will gain sentience and take over the world seems less of a threat than if a GPT-n with revolutionary capabilities and a very restricted number of people that have unrestricted access to it help its unscrupulous owners to take over the world. The owners might even decide that as "effective altruists" it's their duty to take over to steer the planet in the right direction, justifying anything they need to do. Suppose such a group of people has control of Google or Meta, can break down all internal controls, and use all the private data of the users to subtly control those users. Kind of like targeted advertising only much, much better, perhaps with extortion and blackmail tossed in the mix. Take over politicians and competing corporate execs, as well as media, but do it in a way that to most, it looks normal. Discredit those who catch on to the scheme.