If I had a gauntlet with essentially unlimited power, and my goal was to help make sure life in the universe was able to prosper, then my first thought toward this goal probably would not be
to extinguish half of all life.
This doesn't directly help anyone, and it is, at best, a temporary solution, since
populations will eventually grow back.
Assuming that I am not, in fact, secretly in love with an avatar of death itself, why would I choose to
commit universal genocide
instead of directly solving the limited resource problem?
So, to be specific, my question is: In-universe, what is Thanos's motivation for attempting to do this instead of more reasonable alternatives?