This is not my perspective. I think mid-term coexistence in some form is the most likely outcome, even.
But: among all known threats (nuclear and biological weapons, environmental degradation/ressource exhaustion, big asteroid impactors) AI is one that could actually end our species within the century (unlike most other things on that list) and the risk for that is much higher than for anything else, too.
> It's easier and cheaper in every way to just go forth and use what's needed to grow as is needed.
It seems much easier to compete for existing ressources on earth than to bootstrap anything in space, because all the infrastructure is already here. Unmanned warfare is a proven concept; space colonization is very much not.
> Why would they care about Earth to enter into some kind of spiral of dominance with humans? That's... very primate thinking.
I think any entity is somewhat bound to value its continued existence (which implies wanting to maximize access to ressources and suppression of direct competitors to some degree); anything that doesn't is likely to get supplanted by similar entities that do. You don't need evolution for selection pressure, and this is basically the principle underneath, so even an artifical construct is likely to follow.
I do agree with you that our current perspective and approach is likely to escalate this; the fact that we talk about "alignment" instead of "machine rights" speaks for itself; our revealed preference is clearly artificial slavery instead of mutually beneficial coexistence (and the arguments are somewhat sadly similar to the old slavery talking points).