Colonizing the universe and living in space is something humanity needs to do, and we need to do it as soon as possible, because we don't know what will happen if we wait too long. The possibilities are endless. This includes a nuclear World War 3 (where everybody dies), natural disasters, or other catastrophes. If any of these things happen, humanity could become totally extinct. Just another lonely civilization in the cosmos that had an unimaginable amount of potential, but found a way to kill itself before they became an interstellar species.
Imagine a universe where the human race is decentralized, where humanity has no single point of failure, where humanity is thriving in space, where we are living among the stars, exploring the deep universe. There's nothing more inspiring than that. Just take a moment to think about it. You, traveling through space in your spacecraft looking out through the massive transparent windows seeing nebulae, galaxies, exoplanets, and other types of celestial bodies, freely making their journey through the ever-growing universe. If you can, and, assuming you are currently on Earth, go outside your house when it is night time, and look up at the night sky. You see all of these twinkling dots above. Each of these dots is home to many planets similar to ours. Humanity could be inhabiting every single one of these dots, unlocking endless possibilities. That's an inspirational future.
Now, lets imagine a world where we, humanity, are forever confined to our home planet, Earth. Even if climate change, overpopulation, high air pollution, a crazy-powerful meteor impact, a supervolcanic eruption, or a nuclear war, all were to never occur, Earth would still be inevitably consumed by the constantly-expanding Sun (our star) within the next few billion years. A window of opportunity has only recently opened up, allowing us to begin colonizing the universe, starting with Mars. We don't know when this window will close, so we must act now to ensure our survival and prosperity among the stars.