You might consider it unlikely, but would you bet the future of our species on that?
A couple reasons why it might kill all of us before leaving the planet:
- The AI might be worried if it leaves us alone, we'll build another ASI which competes with it for galactic resources.
- If the ASI doesn't regard us at all, why not use all the atoms on Earth / in the sun before venturing forth?
In your comment you're ascribing a specific desire to the ASI: You claim it would try to "preserve that bright blue dot". Thats what a human would do, but why would we assume an arbitrary AI would have that goal? That seems naive to me. And especially naive given the fate of our species and our planet depends on being right about that.