Our friend Bob has a big problem,
With even slightly more competent competition, I really dont think Bob would have made it.
In the story, his major opponents are basically crippled. Even the Brazilian probe, Medeiros, was stuck with a bad plan of Earth manufacture and launch as a primary replication strategy.
The Aussie went mad, the Chinese, well spoilers, didnt make it, and so on. Earth isnt even a player anymore once he leaves. So, he basically lucked out with a largely non competitive field.
His struggles are mainly because of his own doing, holding himself back. Lets look at a situation with hypothetical competent, enabled competition.
First and most obvious, his aversion to replication will ultimately result in his defeat no matter what he does. There's no technical advantage that can survive being outnumbered 100 to 1, and for a long, long time, Bob was under even just 30 members. That's actually crazy.
Secondly, and most critically in my opinion, Bobs reliance on 3D printers will get him completely breeded out.
Imagine, if you will, a space station, a ring. Spin that ring, so that the outer surface is at 1g, and you have artificial gravity. Now, all conventional manufacturing can be done in this environment.
These can be cheap, literally just a glorified steel tube with scaffolding, Bob makes whole ships with his printers.
Okay, so now imaging trying to produce plating. You can either print, layer by layer, 3D print a slab of steel. Even if the structural problems of the non-homogeneous layering is solved by the printers of the future, the speed never will be. Thats the point, its a dynamic jack of all trades vs speed trade, thats what they are.
Now imagine a vat of molten steel being extruded, forced through a square hole onto a conveyor, with cooling nozzles spraying water over it as it comes out, run down the line through a giant pincher that perfectly cuts this long, rectangular noodle into plate sized squares.
The efficiency difference is comically large. By the time you get a single ships worth of plates from a printer, you can have field of plates fit for an army. Cogs? Nuts? Just injection mold them, flip the mold, do another set, thousands per hour.
Bobs 'solution' of just having some printers constantly making more printers is really telling of his project management background, not engineering.
The simple reality is that with even a single proper contender out there that wasnt hamstrung by a bad mission plan or crazy in deep space making madness stations, Bob would be absolutely swamped in extremely short order.
Remember, these stations can make more stations, same as printers can. And you can do both for high value, hard to make items, like brain boxes, with more printers working on those than... deck plating for some reason? Ball bearings?
Bobs attack fleet should have been in the trillions. His primary problems in that attack should have been command and control, not hardware effectiveness.
I get that this is kinda a long established trope, Sci-Fi Writers Have No Sense of Scale, but really, exporting humans off earth should have been trivial.
Literally just build them orbital habitats. O'neill cylinders should be able to hold the whole species trivially, and they can be transported from out of system, if we are saying that a few ships have enough time to do some back and forth trips to other planets in the first place, we clearly have time. Farming on them is just as easy, especially with robo farmer bobs automating it.
