There's not much the other factions can do by the time they attack. Granted I tend to cheat cash in so I can start pumping out an early military, mainly because I'm actually bug hunting and not doing a proper playthrough, so I can get through all possible content as soon as possible to cover it all, but not even all of them combined with a beefier military could take my 1 Sword of Entropy, 60+ dreadnoughts, 120+ battleships, 240+ cruisers, 480+ frigates, 960+ bombers, 1,920+ fighters, and 3,840+ combat drones. Yes, I am that anal about having an overwhelming military that just can't lose and, yes, I have been playing this save for an extremely long time.