I think 'sell out' is a VERY relative term, and to me, pretty pointless, if not just ignorant.
IF you are in a band that makes that light-speed jump from playing clubs and dance halls and a year or two later you're touring behind a #1 album, the question doesn't matter: It's already been made for you.
You're suddenly dealing in cubic feet of cash, you've got busses and 18-wheelers to keep on the road, a crew of 4 dozen minimum, tee-shirts and Frisbees to sell, and on and on. You're now incorporated, and looking to make all the right money decisions an LLC with a seven or eight figure income has to make. And on and on. And all of this has nothing to do with the music and the feeling for music that brought you together. And you have to keep those original feelings while dealing with all of the above and more. Fortunately you're hopefully still a year or two out from the rounds of divorces, paternity suits, rehab, drug-sniffing dogs and egos gone wild, and beginning to payoff the mountain of debt you've accrued. OF COURSE each one of you should have your own coach, why stay crammed into that Prevost with THOSE guys . . . .
Now maybe, you really can't shake that feeling you DID sell out, and you're willing to walk away from your Porsches, the house in the gated community in Marin County or The Hamptons, and the money and the gigantic, ego-stroking, head-swelling, sweet smell of success.
Go ahead. It's OK. Go.
And some will. And most . . . . . won't. What the hey, it sure beats working for a living !?! And that's the point: Any fool can get lucky and be a one-hit-wonder, but to have a career that works for years, it's an ever evolving blend of art and hard work and business. Sorry kids, maybe I'M a sell-out !