Why does Hawking want humanity to leave Earth as soon as possible?

The famous physicist Hawking passed away 3 years ago and some of the things he said while alive are still widely discussed. For example, Hawking believes that sooner or later, humans need to leave Earth.
The Earth has gone through a period of 4.6 billion years, and by this measure, the time of human life on Earth is still very short. Homo appeared on Earth only 2.5 million years ago, and Homo sapiens, the ancestor of humanity, barely evolved until 200,000 years ago.

For the past four billion years, life on Earth has been endless. But now on Earth there are only nearly 10 million species of creatures, this number is only 1% of the total number of species that have ever lived on Earth, the remaining 99% has disappeared in the long river of the Earth. Although our planet is a vibrant planet, it is very difficult for any living species to survive long on Earth. Over time, the Earth’s climate will continue to change and some ancient species have been unable to adapt to this change, leading to extinction. In addition, life on Earth could also be threatened by deadly threats from space. For example, a gamma-ray burst from a supernova could destroy Earth’s atmosphere and cause deadly cosmic radiation to reach our planet’s surface. Most life on Earth wouldn’t be able to withstand this. 450 million years ago a supernova caused the first mass extinction of the space threat on Earth. On the other hand, the impact of a giant asteroid falling to Earth will also cause drastic changes in climate, disrupt the food chain and cause mass death for life on Earth. The fifth mass extinction 65 million years ago was probably also caused by an asteroid collision. In addition to the threat from space, on Earth there may be superbugs that humans can’t fight off. Humanity also possesses nuclear weapons capable of destroying all life on Earth. Although humanity has enough intelligence to create such a powerful weapon, it is not known if humanity is intelligent enough to not use nuclear bombs on a large scale. And also for various reasons, Hawking believes that in order to continue to exist, humanity must expand its habitat into space in the future. Only by taking precautions and leaving Earth before disaster strikes and colonizing other planets can humans better cope with unknown disasters. So which planets should humans migrate to? Is there a “Second Earth” in the universe? Proxima b’s host star is Proxima Centauri – part of a trio of strange stars that scientists are still studying. The other two stars are binary – meaning they orbit the same center of gravity and are collectively known as Alpha Centauri. Although this “Second Earth” has similar properties to the Earth – where we live, Proxima b is still a mysterious and alien world. In the solar system, although life can exist on some satellites, but apart from Earth, there are no planets suitable for human existence. To achieve the goal of space colonization, we can only look beyond the extent of the familiar solar system. Current statistics show that almost every solar system has planets, and there are hundreds of billions of stars in the Milky Way, so there should be multiple targets to choose from. People need to choose rocky planets that are in the habitable zone, because only when the distance between the planet and the sun is neither too close nor too far can liquid water exist on its surface. Proxima b exists right in the middle of the habitable zone of stars, where water could theoretically exist in liquid form. Compared to our sun, Proxima Centauri’s habitable zone is very close to its host star. Scientists once believed that red dwarf stars like Proxima could not exist on habitable planets that were orbiting so close. But now, scientists think red dwarfs might be the best place to look for other habitable planets. And recently, astronomers discovered that Proxima Centauri, the closest star to our solar system, has a planet called Proxima Centauri b. This planet is a rocky planet the size of Earth and it is also in a habitable zone. Although Proxima b is the closest exoplanet to the solar system at a distance of only 4.2 light-years, humans are currently not capable of flying to this planet. Even with today’s fastest spacecraft, if we want to set foot there, it will take us tens of thousands of years to fly to Proxima b. However, humanity has never backed down from difficulties, we have been able to cross the ocean, as well as cross the distant interstellar space to reach the strange world, so it is very possible in the future , people will set foot here.