How do record companies may profits from Rap & Hip Hop albums sales?

Using Amazon, iTunes and Billboard Charts, there always seem to be one
or two Rap or Hip Hop albums in the top 100 album sales.

I realize that those genres are very popular (especially in strip
clubs) and that the album sales are diluted by illegal downloads,
YouTube and other alternative media outlets. However while the artist
themselves are still able to earn a sizable income through concerts
and movie/tv roles and appearances, it is hard to see how the record
companies make money off them.

This is not a bash against Rap or Hip-Hop. I just wonder how the
economic reality of the music supports it.