Similarly, you think that x-risk dismissal among the experts you agree with is not self-interested - but it's not like the oil and gas engineers dismissing climate change risks would describe themselves as self-interested liars either. They would likely say, as you realize, "No, my dismissal of the concerns of other experts is legitimate!"
The thing is, it doesn't require a lot of expertise to understand that there is actually an enormous risk and "experts" denying that are simply burying their head in the sand. AI, I use the term expansively, is making huge and rapid progress. We are approaching "human-level" intelligence and there is no guarantee, nor even any indication, that "human-level" is an upper limit. Systems as smart or smarter than we are, that are not controlled for the benefit of humanity, are an existential risk.
There are two basic kinds of risk. First, an AI powered tyranny where a small number of humans dominate everything enabled by AI systems they control - every security camera watched by a tireless intelligence, drones piloted by perfectly loyal intelligences, etc. Second, that the AI systems are not effectively controlled and pursue goals or objectives that are incompatible with human existence. In either case the fact that the AI brings superhuman intelligence to bear means that humanity at large will be overmatched in terms of capabilities.
It is completely possible that neither of these scenarios come to pass, but the fact that one of the scenarios might come to pass is what makes the situation an existential risk - humanity eternally subjected by an irreversible dictatorship, or simply destroyed.
I'm confused about your first item that would convince you of AI risk, but I think the others should all be considered met by ChatGPT. Of course, ChatGPT isn't currently useful in developing new WMDs - but it is absolutely useful in helping to bring someone up to speed on new topics in many different domains. As capabilities advance, why wouldn't ChatGPT using GPT-5, or 6, or 10 be able to helpfully guide the creation of new and better WMDs?
AI isn't currently causing the problems you are worried about but certainly seems on track to do so soon. "Risk" doesn't mean that we are currently in the process of being destroyed by AI, but it does mean that there is a non-negligible possibility that we will soon find ourselves in that process.