I never said they would do it on their own. Your counterexample is not a counterexample, but an example of what I said would happen.

DPRK manages this shit, it's in the reach of any nation-state.

this stuff is vastly easier than traditional weapons development.

if you're in a precarious political position, a homegrown entity that produces these tools can quickly become a threat; the citizens you train/employ will have their own political ambitions, nationalistic tendencies, empathy for their fellow citizens, etc.

there are most certainly situations where it's safer to just outsource your natsec/tradecraft to an entity that only cares about their bottom line.

> this stuff is vastly easier than traditional weapons development.

Saudi and Mexico don't produce many homegrown weapons systems either. Again, non-proliferation is well-travelled territory. In fact most of these things are not something small governments will have access to if big governments don't give it to them. And treaties restricting trade in these things are known to work.