Is a band that sells 20,000 overpriced tickets relevant? Whether I want to think so or not, probably.... Relevant, popular, it's a sticky argument. Is Beyonce relevant? Is Usher relevant? They can sell the hell out of a concert, though.
Point is, they can sell the tickets. I'd say I find it amazing, but I just paid $200 to see U2, so who am I to point fingers...
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Better example, I paid close to $200 (I think...) to see Simon and Garfunkle. NO WAY they are still 'relevant,' whatever that means, but damn if they're not icons and I'd never seen them before.