If we define the "complete well-being and flourishing of humanity" as the highest universal value of the human world, it must inherently encompass one of the most crucial spiritual ideas: "a reliable distant future."
To colonize habitable exoplanets, humanity will need not just one millennium. There is time for this, as planet Earth, with careful treatment of nature, will remain habitable for tens of millions of years. But for this, what is primarily important is the fullness of love for life and dreams on planet Earth.
Modern humanity must ask: does it not jeopardize the aspirations of its ancestors and the expectations of descendants with its arrogance and shortsightedness?