See, you said all of these things and then slipped into the sci-stories.
What about, instead of that, grey goo physics defying replicating nano bots aren't real?
People do this thing where they think that if you just linearly increase inteligence that this lets you invent magic overnight, and thats simply not how it works.
The magic takes a lot of time, energy, and resources, if it were even to be possible at all.
There is literally concerns over mirror life being developed. The point is that if a system that has high reasoning capacity to solve logistical and mathematical problems, it may be able to come up with a mechanism you, puny-to-it-human, may not be able to predict. It may use technology not yet known to humans (one that it has designed itself), or may use already known technology, but figure out how to scale it up enough to cause earth-wide disaster for humans.