No, its not ridiculous. What's ridiculous is our approach to the problem. Reconstructing Earth's ecosystem away from Earth is a monumental task in any situation

No, its not ridiculous. What's ridiculous is our approach to the problem. Reconstructing Earth's ecosystem away from Earth is a monumental task in any situation, whether you want to terraform a planet, build a orbital colony or just have a universe ship to send somewhere. These are decades or centuries long efforts which are solely for the purpose of catering to the current, Earth-optimized human form. If you want to head out into the universe, develop a new form. Adapt humanity to the place you want to colonize, rather than the place to humanity.