I'm a big fan of 80s glam metal music such as Poison, Def Leppard, Whitesnake, etc, and I have noticed that there doesn't seem to be a single non-white performer in this genre of music and few if any non-white people listen to the music. Does anyone know why this may be? Plenty of white people perform and listen to rap so why not vice-versa?

You would have to go back to the 80's to find out. The short answer is that there wasn't a huge interest at that time. There was lots of competing music going on.