I also wonder about the "now it's time to lift everyone else into abundance" earlier in the article. I don't disagree that this is valuable, but it doesn't solve the existential "why", it just puts it off for a few decades until the poorest humans are as rich as wealthy Americans are now. "What a problem to have!" one might say, but literally that is the problem that the article is about, right? Going back to power-level everyone else doesn't actually solve the problem of what to do when someone reaches the level cap.
Ultimately there is nothing that is obviously and provably more important than the individual reading or writing this, as there kinda was in previous eras. Some candidates include religion, panhuman expansion or thriving (Musk), building a successor entity or entities (Altman), and the State or politics (the OP). I don't know of any argument better than personal preference, at the moment.