Well, that's a shockingly ignorant and dehumanizing mischaracterization of nomadic societies. Ever hear of the Mongols? They were nomadic pastoralists, and they built the largest land empire in pre-modern history. Similarly, Arabs have historically been largely nomadic, at least pre-Islam, and they built one of the most widespread and enduring civilizations on Earth. Nomads are great at cooperating. They just do it on the move.
Nomads don't live a migratory life because they're incapable of sedentary living, but because migratory living works better in the ecological niches they occupy. The racist myth is that nomads are more primitive than sedentary civilizations, but in fact, they mostly descended from sedentary civilizations and adopted nomadic living once they obtained domesticated camels or horses, because that lifestyle enabled them to develop environments that sedentary populations had been unable to develop, such as the desert or the steppes.
Nomadic communities are small individually, but they are groups of dozens or hundreds of people, who naturally have to cooperate among themselves. And they have no problem working together in larger groups when it's necessary to do bigger things, like elect a new khan or conquer most of Eurasia. Many nomadic societies have a number of fixed regional settlements that they periodically migrate among from season to season, e.g. a winter home and a summer home, so there's always a fair-sized population within each settlement even though it's not the same people year-round.
As for the Hirogen, it's true that as predators rather than omnivores like humans, they would tend to organize in smaller population groupings, probably something more like the size of a wolf pack, say, and would not cooperate with outside groups as easily as humans do. But clearly they have enough technological sophistication within each band to build and maintain starships, which has got to be orders of magnitude harder than building holodecks.
