LLM-based agents don't have to be super-intelligent to cause massive damage. After all, the Black Death killed 1/3 of Europe and no one thinks it was conscious. It suffices to have large numbers of agents pounding away at the Internet, powered by millions of dollars in compute power, trying to reach odd corners to satisfy a goal, using every tactic they copied from Stack Overflow or hacking contests, with no knowledge of the side effects their actions may cause. Internet-connected systems have massive numbers of security holes and really stupid attacks can produce bot farms even before LLM AI came along. Enough life-critical systems are connected to the Internet that a massive, stupid agent-based attack where neither a person nor an agent "decided" to cause harm could produce a disaster. So I don't think AI is going to become super-intelligent and kill us all, but do think that stupid AI could make the Internet unusable at some point.