While Ozzy Osbourne might pop up in The Sun and Metallica have sold over 100 million albums, metal as a whole is still not mainstream.
The essence of metal's sound and image makes it underground - an alternative choice from the norm that is still misunderstood and maligned with negative stereotypes.
A case in point is the British band Iron Maiden, who have become one of the world's biggest and best loved bands ever without anything in the way of consistent longterm exposure in the mainstream media.
Why? Because they're metal.
Nevertheless some subgenres are more underground than others, often based on the reduced accessibility of their sound: e.g death and black metal.
Do we care? Do we hell.