It will be interesting to see if later phases make Thanos' plan more rationale. Maybe by having the overabundance of life in the universe attracting Galactus or something.
It is interesting to note that every character who Thanos agrees to spare doesn't grt snapped.
I was just thinking that myself.
I imagine that if it were truly random half of the timelines probably involve Thanos snapping himself and then Thor (or someone else if Thor was snapped) just picking up the gauntlet and snapping everyme but Thanos back into existence.