Thanos thought his heart was in the right place when he decided to wipeout half of the universe in Avengers: Infinity War. Though his thinking was a bit unorthodox, it was based on trying to do something positive, but it definitely would not have helped out Earth all that much, according to Justin Christensen of the UCLA Physics Department. Christensen decided to take a look at the Decimation and its effects on Earth as a primary focus for obvious reasons.
There has been some debate as to whether or not the Decimation in Infinity War wiped out all living things or just sentient life, aka intelligent and conscious life forms like humans and animals. Screenwriters Christopher Markus and Stephen McFeely have confirmed it is only sentient life, while Marvel Studios boss Kevin Feige has said it's ALL living things, which makes matters even worse. Going back a bit, if Thanos were to dust half of the world's 7.6 billion people, we'd be left with 3.8 billion people, which brings us roughly back to 1970, in terms of population.
The world was still booming with 3.8 billion people, so Thanos wouldn't have done all that much in terms of starting over and providing more resources to people. However, as seen in Infinity War, there were people driving cars, flying planes, and doing other activities when the Decimation happened. Physicist Justin Christensen estimates there are as many as "20,000 airplanes in the sky, worldwide, at any time," which is easy to see where he is going. If each of those planes has around 200 people on them and a pilot is Decimated, that's nearly a million more deaths, not counting what happens when the planes crash. Never mind thinking about air traffic control at this point. It would be utter chaos.
With half of the humans and animals gone on Earth, there would be major changes in the food chain, says Justin Christensen. Humans would be able to get the population back to normal in a bout 20 to 30 years, but the food chain and ecosystem could be heavily effected for animals who don't reproduce quickly. We could see fresh water and other sources of food corrupted, which would also not be a very good thing. With the ecosystem under strain, life would change a lot for humans.
If we're going with all living things, like Kevin Feige claimed, the results of Thanos' Decimation are even worse, according to Justin Christensen. That would mean everything from the plants that we and animals eat to the organisms in our stomachs to digest food would be effected, which would be catastrophic. In the end, the Mad Titan was trying to make a positive change for the universe, but when looking at it scientifically, he would have done a lot more harm on Earth than good. Maybe he should have doubled the resources instead? You can read more about what Justin Christensen had to say about the scientific effects of Infinity War on Earth over at Fandom.