Let us set aside opinions as to the usefulness of such a venture for a for a brief spell, and ponder as to whether it is even an endeavor our stage of civilization is capable of.
Sometimes it is instructive to delve into our historical past and see if one can draw parallels with deeds performed by our ancestors, comparing them to our own experiences with the caveat that there may be similarities, but also strong differences.

There they stand, constructed some 4800 years ago. The Great Pyramid complex on the Giza plateau is truly a breath-taking monolithic, remarkable structure. It is hard to comprehend that the individuals who created this did so at the very dawn of their civilization, during the First Dynasty. To be sure, there were pyramids constructed in the Middle Kingdom and during the Late Period, but we only know where these stood. They are gone because, compared to the earlier structures, these did not stand up to the test of time.

For emphasis, it is worth mentioning again that these structures are truly breath-taking and if you have not had the privilege of seeing them, the repetition of emphasis is not a waste. One can stand in gob-smacked awe staring at these over-sized monoliths, trying to wrap one's mind around the notion that the early Egyptians overcome the organizational, technological and architectural hurdles necessary for these structures to come into being.
Carving limestone with bronze age technology, dressing red granite on an elaborate scale. Persuading and organizing the construction could only have been have been a political and logistical masterpiece.
Most archeologists agree that the early pyramids were not the result of slave labor, the quality of the construction alone suggests otherwise. The exactitude of measurements of these grand-scale Giza structures is such that the error could be covered up with a thumb, well beyond any specifications expected of 21st Century construction.
The Great Pyramid incorporates Pi and a unit of measurement based of the circumference of the Earth, discoveries what were until relatively recently, attributed to the classical Greeks some 2,300 years later.
Although there is disagreement amongst archaeologists, this structure seems to have served no overt practical purpose. The funerary monument concept is in dispute because no trace of bodies were ever found inside them, apart from an intrusion burial from a later age in the smallest one. *

Now, consider the overall resources available to these ancient Egyptians at the dawn of their civilization, to the immense technological, scientific and logistical capabilities we can marshal today.

...Can you really tell me, in all sincerity, that we can't colonize space?

* "Secrets of the Great Pyramid" by Peter Tompkins.