Throughout history there have been hundreds, if not thousands of examples of people and groups who thought the end of the world was imminent. So far, 100% of those people have been wrong. The prior should be that the people who believe in AI doomsday scenarios are wrong also, unless and until there is very strong evidence to the contrary. Vague theoretical arguments are not sufficient, as there are many organizations throughout history who have made similar vague theoretical arguments that the world would end and they were all wrong.
https://en.wikipedia.org/wiki/Category:Apocalyptic_groups