You're conflating three different things.
There's the question, "is an LLM just autocomplete"? The answer to that question is obviously no, but the question is also a strawman - people who actually use LLM's regularly do recognize that there is more to their capabilities than randomized pattern matching.
Separately, there's the question of "will LLM's become AGI and/or become super intelligent." Most people recognize that LLM's are not currently super intelligent, and that there currently isn't a clear path toward making them so. Still, many people seem to feel that we're on the verge of progress here, and feel very strongly that anyone who disagrees is an AI "doomer".
Then there's the question of "are we in an AI bubble"? This is more a matter of debate. Some would argue that if LLM reasoning capabilities plateau, people will stop investing in the technology. I actually don't agree with that view - I think there is a lot of economic value still yet to be realized in AI advancements - I don't think we're on the verge of some sort of AI winter, even if LLM's never become super intelligent.