But... why would we want to live in space? We're adapted for life on our blue-green planet. Why bother incurring enormous costs when there is literally nothing at all that can't be done in space better by robotic missions? I literally can't think of a single valid reason why any human being would opt for a long-duration period off-planet, never mind incur the phenomenal costs & risks associated with such an undertaking. Sure, silly billionaires and government agencies spend money on such dreams, but that doesn't make the idea reasonable nor achievable. Unless we have a compelling reason for long-term habitation in space I rather suspect it will remain the stuff of teen-audience sci-fi.