It's not so black and white as that, actually.
Some white people do use the N word, ... but if they use it publicly (i.e. outside of their niche), there will likely be consequences.
Black people may also use the N word, and will also face the consequence of their usage of it. The word is rarely used publicly, except in extremely niche commercial ventures. Black people can get into serious (life or death) trouble for using the word to offend their hearers, ... otoh, if its use is intimate ... and not for offense, ... then it can be acceptable to some hearers.
I dare say most of American blacks don't use the word, and its usage is certainly frowned upon socially. Though, once again, there is a small niche of the black population which will use the word (in their social settings) for street cred.
The N word is used, by those blacks who use it non-offensively, as a way to take some of the sting out of the word by taking some control over its usage.
For reasons of personal circumstance, non-blacks cannot claim to use the word in any of these more non-offensive ways. Their usage of it will publicly (i.e. outside of their own circle), will almost always be seen as being offensive, ... and consequences for its use may have to be faced.
It's really not a situation where some may use the word ... and some may not, but that ALL must be prepared to face the social (or personal) cost ... of using the word.
