Elon Musk estimate over a billion of humanoid robots. In 10 years? 20 years? He's usually off with his timelines. Many of the problems we currently have cannot be fixed due to limited manpower and also the expense of paying humans to do jobs. But if a robot is 1000 times cheaper than a human being, can go in dangerous places, can work 24/7, then more problems can be fixed at a much quicker rate. We can get these robots to clean the oceans. We can get these robots to plant millions of trees / Terraform the Sahara Desert.