The popular definition of sell out allows it to be used as an insult towards anyone in show business. On the contrary, there are many bands which are considered sellouts which are not.
For instance, Green Day. They are considered sell-outs because they are a punk band who was popular on MTV. Green Day never stated that they would never be on MTV, thus they are not sell-outs in that sense. They never changed their musical style for monetary reasons, thus they are are not sell-outs in the more literal sense of the word. If Fugazi were to sign up with Sony records, they would be selling out because they preach against major labels.
2. When an artist conforms to the way they believe their fan base see's them.
3. When an artist gets too big for their own good, and believe that they are god(s) and can do anything they want.
4. When an artist changes their play style to make more money
5. An artist which no longer does it for the fans
2. The Darkness.
The anger comes from the false belief that fans "own" their favorite entertainers, that these entertainers are thus not real humans with free will, and the feeling of grief when some CD that the listener previously enjoyed alone is now enjoyed by millions of more people.
(Note that "sellout" ONLY applies to those who make a living in the fine arts. For example, a software engineer who accepts a job promotion and higher salary is never branded as a "sellout". Nor is a professional athlete who appears on a box of Wheaties.)
(1993) "Damnit, Smashing Pumpkins is such an underrated band. They never get played on the radio!"
(1994) "Damnit, Smashing Pumpkins are always on Mtv and the radio now! They're such sellouts."
That band alienated their fan base and changed their style according to what the record company wants, that means they're sellouts.
OMG THAY SOLD 30,000 RECORDS?!!11111 WAT SELLOUTS....
OMG THAY GOT ONTO TV???/// SELLLL OUTS
OMGZZ THEY R GETING SPONSORED BY SUM BIG COMPENY??// SELLOUTS!!11111