As per the difficulty and cost of space travel - it took in the order of hundreds of years of development for several impactful technologies to be tinkered and optimized to a point where they started to make a difference. Steam engines, mechanical watches, etc.<p>E.g. the first watches that could keep time to assist in measurement of the longitude were incredibly expensive <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;John_Harrison" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;John_Harrison</a>.<p>I know historical arguments are usually kinda weak but objectively - space flight is still a young discipline.<p>I hope you respect that in historical perspective &quot;we&#x27;ve never done it and so won&#x27;t ever do it&quot; is really weak. It will require empirical testing to figure out if spacefaring human civilization is a tenable concept. Large system cannot be reasoned with beforehand (well, if there are deep physical principles that are obvious then, yeah, sure, but at this point the problem space appears like more like a complex expensive mess of many uknowns rather than a physical impossibility).