Because "paramilitary" isn't really up to the standard of military, as a rule. Paramilitaries can range from full military-style training to just giving a rifle to everyone in the country in a certain age range and telling them "you're in the militia." Especially if they have around a quarter of the whole country in the paramilitary, I would be wary about considering it an effective fighting force.

 

Agreed, we're not debating the effectiveness of North Korean paramilitary forces, just it's reported numerical strength. 

 

In contrast to North Korea, paramilitary here in the states, most notably Police since there isn't militias anymore, is often quite well trained, with many coming from a military background. 

 

It becomes evident that North Korea doesn't have the resources to provide appropriate, adequet equipment and training and instead rely on numerical advantages to appear threatening.  

Even though NK might have the largest army in the world, they would be heavily defeated, in part due to their old technology, and weapons.

 

Cheers.