"He didn't double the resources in the universe because that's not what he's trying to accomplish, and also because he's an unhinged, sociopathic supervillain who is basically on a holy crusade. Thano's plan only has to make sense to him, and in terms of fitting his character, it's perfect."

Exactly, people forget that he's a genocidal maniac. If you look at his plan more closely it's clear that it doesn't really make sense. It's his way to justify his actions to himself.

Because in the comics, Thanos was literally in love with the physical embodiment of death and wanted to impress her. But that's too weird for them to ever do in the movies.

To make more money.

In marvels point of view