I guess the piercing of my suspension of hard sci-fi disbelief happened in the 2nd book(?), where post-Fall they rebuild into a militarily space capable society

I guess the piercing of my suspension of hard sci-fi disbelief happened in the 2nd book(?), where post-Fall they rebuild into a militarily space capable society with relatively advanced weaponry. If you're going to take 1,800 pages (English translation) to lay out your series, and you can't spare a few for 'well, now we're building giant fusion-powered warship fleets'? That's not anything approaching hard sci-fi in my book. Yes, all the technologies used on the ships are extrapolated and believable, but the realignment of society, economics, and the organization of such a construction effort boggles the mind. And to say 'it just happens'? That's kind of like going from WWII to 'and so we landed on the moon' in a single page.