I don't think that killing all biological life is a conclusion that a purely rational AGI would have.
I also don't think the shitty and egoistic behaviour of most humans can be explained by egoism.
I also don't think the shitty and egoistic behaviour of most humans can be explained by egoism.
Any goal with "but don't kill everything" added is more complicated than the version without that stipulation (and that specific one only saves a single microbe). The simple goal is easier to accomplish, so free market competition guarantees we'll try it first. Biological life is not compatible with "make number go up" taken to its logical conclusion.
There is no need for the ASI to be conscious or to have any equivalent of human emotions to make the number go up.
Fortunately there's a really simple solution to offer it, in just wiring measurement to "prediction" directly (perfect correspondence, and much lower effort than annihilating Life and removing the atmosphere). And I don't particularly believe a system like that can be a general problem solver, much less one that climbs to World-jeopardizing influence on its own.