I am all for space colonization but i realize it's a fundamentally egocentric thing to wish for. It's not really what nature intended. We have eleminated many other species and at some point in time the same fate will probably await us.
Nature intended for me to die of starvation within weeks of being born due to a congenital disorder preventing me from digesting anything. I'd wager that nature probably didn't intend for you to have 20/20 eyesight, or to have all of your teeth, or for you to type on a magic glowing box that allows you to communicate with people halfway around the planet.
Is self-preservation egotistic? Probably. An asteroid similar to the dinosaur extinction event could hit us at anytime, with a few hours notice. You'd think the human race would learn from the dinosaurs?
Imagine another asteroid hits Earth, humanity becomes extinct, and a new sentient species evolves after 200 million years. This species will dig up human and dinosaur bones. Reminds me of: "Fool me once, shame on you; fool me twice, shame on me."
Nature didn't intend anything. There's no such thing as an integrated, thinking, conscious entity called nature that intends some distant outcome.
An example that makes the point: nature intends for us to spread to every habitable planet in the galaxy. Nature wants humanity to dominate.
There is also no such thing as fate. Humans aren't fated to a pre-set outcome. If I step on a spider, that doesn't mean bad karma is going to have a tornado rip my house apart. If some humans cause the extinction of some species, that doesn't mean the human race is going to be wiped out.
Depends how you look at it. Our bodies are built to live on parts of this planet in this specific era. We don't do so well in space and microgravity. We're not going to do so well on Mars, or Mercury or Triton. That's never going to change.
Judging by the history of this planet, if nature intends anything it's for life to spread into every niche imaginable. Colonizing the solar system is just more of the same, and if we do it right we'll bring lots of other species along with us.
If we're not on two planets in any meaningful way, it only takes one big rock to be on zero planets.