Say what you will about Thanos as an uber-villain; he does get shit done. He found a problem with the universe and used some out-of-the-box thinking to solve it. Was it a popular decision? No. But what is the right one? That’s kinda up for debate.
His plan, to eliminate 50% of all life in the universe, was supposed to bring balance and harmony to the universe. With half the humans, Kree, space pirates and Skrulls roaming around and using up resources, every planet was supposed to become a paradise.
Without seeing what the universe looks like in Endgame, it’s hard to know for sure. Makes you wonder what would really happen if Thanos’ snap really did do the thing.
Let’s ask science.