The fact that you don't solve starvation by killing half of the farmers and food scientists is never mentioned, and in fact, it's not even clear whether the screenwriters realize it. You need people to produce the stuff.
Back in the year 1400, the global population was somewhere in the 350-400 million mark. Today we're in the ballpark of 7.6 billion. Do you think the average person's life was better then, or today? Well, you're reading this on a magical device that contains the totality of human knowledge while you're busy not painfully dying from a minor infection you picked up working dawn to dusk, so there's your answer. Those billions of people include lots of scientists, inventors, doctors -- smart people who known how to turn useless rocks into tools and poisonous mushrooms into medicine.
Thanos talks as if "resources" are naturally occurring boxes of clothes and food that we're consuming too quickly. In reality, it's all shit that was lying around until a living being figured out how to make use of it. So the most valuable resource people have access to in the entire Universe is other people. How many of you are working somewhere that would magically grow happier and more efficient if you had half the employees?
Yes, there are inefficiencies and flaws in the system, which is where our ( completely inaccurate and misguided) fears of overpopulation come from. Wars, poor infrastructure, and disasters create famines, not overpopulation. Humans are, in fact, the resource we can least afford to lose. The film acts like the only reason to keep them around is that killing is mean and losing our friends would make us sad.