If you are going to land a critique, use specifics.

What specifically did I say that indicates I do not know Hip-Hop well?
I grew up listening to it. I’m from New Orleans and personally know some rappers who have broke into the mainstream.

There’s nothing wrong with questioning someone’s understanding (or authority) on a topic. But at least make it make sense so that I can understand what your point is. Otherwise it just comes off as a simplistic insult.