The plausible sci-fi scenario from here is obvious. Intentionally bad, or unintentionally bad AI zero days as much as as it can, as fast as it can, copying itself to as many data centers as it can, destroying and/or locking out as many humans as it can. Satellites, military computers, medical equipment, factories, critical infrastructure, you name it - I think we all know none of it is very secure software wise against a SOTA AI that can literally come up with its own zero day attacks.