Getty Musicians James Hetfield (L) and Robert Trujillo of Metallica perform onstage during Rock in Rio USA at the MGM Resorts Festival Grounds on May 9, 2015 in Las Vegas, Nevada.
And now its manager, Peter Mensch, is saying that bands don't really make any money anymore from music, such as CDs or downloads.
Mensch told BBC Radio's Today programme: "the paying-for-music horse has bolted. Money from touring is the way to make money now. Record sales now are about a tenth of tour income, whereas before, you could make enough money from the music to not need to tour."
But Mensch should know what he is talking about - he has and continues to manage some of the world's most famous rocks bands, including Smashing Pumpkins, Def Leppard and AC/DC.
Recently, as my colleague James Cook reported, Metallica's drummer Lars Ulrich publicly backed Apple's upcoming streaming service Apple Music as it pays the artists it streams music from.
Metallica was one of the most high-profile bands to take a stand against online music piracy, and sued filesharing site Napster in 2000 after the band's music was posted on the site. Ulrich read testimony before the US Senate Judiciary Committee, explaining the damage done to the band by piracy. The lawsuit eventually lead to Napster shutting down after Metallica won an injunction that forced the site to remove copyrighted music.