Can you think of any who used to make non-mainstream sounding music, had their own vision and sound but then changed their image and started making trendy music? Maybe they didn't want to do so but they were forced by their record label.
Avril Lavigne and The Best Damn Thing album and Girlfriend. I guess it worked out for her though, big smash.
Avril did exactly the kind of music she wanted though. She was always mainstream and Let Go is one of the best selling female albums of the 2000s. She had been saying since 2005 that she wanted to make a fun pop-rock record because she wanted her next tour to be upbeat. She said she wanted more songs like He wasn't and sk8er boi and that's exactly what she did with Girlfriend and the whole The Best Damn Thing. It's also the first record she was an executive producer on. She went in her own direction where she decided everything for herself for the first time. That's hardly being a sell-out.