Given that we all haven’t been obliterated by nukes, it does seem your argument seems to argue against your own premise. We will probably be fine even if we inexplicably create superior intelligence. Besides? Who’s to not say that the best course of action an infinitely intelligent being would choose is to just switch itself off given the futility of everything?

Don't worry. A sufficiently powerful AGI won't destroy the universe to satisfy its own goals; it'll just build a holodeck (by tampering with its sensors) so that it can gain +infinity pleasure right away.

Unlike software, which can be mathematically airtight, there's no reason to assume that physical devices built by humans are unexploitable in the face of the massive intelligence of the AGI. So the AGI will just ask itself which is easier: delicately performing surgery on its own sensors, or building tons of nukes.

Honestly, that people are even worried about AGI doomsday shows to me the power of narrative. Everybody has heard of SkyNet and the sorcerer's apprentice, nobody has heard of the AGI who outsmarted itself by creating digital porn for its objective function. Therefore, through the miracle of the availability heuristic, AGI doomsday it is.

i'm not as scared of real AGI as I am of some pseudo-AGI convincing enough to fool everyone into following what it comes up with and ascribing it magical powers - we have enough problems with personality cults and herd mentality as it is..