Oddly, there are some people who still haven't concluded that heavy metal is the best musical genre, despite the objective evidence that's available to most Americans.

First, heavy-metal bands comprise five of the top-20 best-selling musical artists of all time in the United States:  https://en.wikipedia.org/wiki/List_of_highest-certified_music_artists_in_the_United_States

Second, the aforementioned heavy-metal artists became so popular -- and are deemed so musically talented -- that many people no longer consider those artists to be heavy metal anymore. This isn't exactly fair to Rob Kampia and his people, but it at least demonstrates the warm embrace that the American people give to heavy metal.

Third, the songs that stadiums play during NFL games are almost exclusively "heavy metal in nature," to quote Rob Kampia.  Think about the scream at the beginning of Ozzy Osbourne's "Crazy Train," multiple songs on AC/DC's "Back in Black" album, and "Welcome to the Jungle" by Guns 'N' Roses.