Just in terms of pop cultural perception. This also doesn’t apply to bands/artists that have openly been super commercial for most if not all their respective lifespans.

The biggest artist in music I would have to say is the biggest sellout would have to be Garth Brooks because from the time he debuted in 1989 country stations were predicting Garth would become the biggest name in country music and scoring hit after hit from his debut album everybody was right. And when Garth Brooks released his second album No Fences in 1990 Garth Brooks was making a huge name for himself with music videos getting constant airplay on CMT and TNN and with the singles The Thunder Rolls and Friends In Low Places Garth was so successful that he actually broke music records but even with competition with Clint Black and other male country artists couldn't hurt Garth Brooks's fame. But when Garth released his third album Roping The Wind in 1991 it was considered Garth Brooks's version of Michael Jackson's 1984 album Thriller and Roping The Wind was actually the album that boosted Garth Brooks's stardom and he soon began winning Grammy Awards and going on tours and nothing could stop Garth Brooks and teaming up with artists like Trisha Yearwood and Billy Joel proved that Garth Brooks would become a legend in country music and so with the albums In Pieces and The Chase "not the game show by the way" Garth Brooks was on a roll but I think the album that made him break a bigger record was the album Sevens and it proved that Garth Brooks was still on a roll and even when he went through a new image and became his alter-ego Chris Gaines Garth Brooks's fanbase still grew and even though marrying Trisha Yearwood made him successful Garth still had time for concerts and even teamed up with Walmart to release a box set of every album with a Walmart exclusive concert DVD it proved that Garth would be as big as Johnny Cash. But if you were to ask any country music fan who is the biggest sellout in country music they will most likely say Garth Brooks