Chuck Klosterman's recent book "The Nineties" talks about this a lot! And honestly it's spot on. I had forgotten about this, and not realized how much it disappeared as a cultural concept.
https://www.amazon.com/Nineties-Book-Chuck-Klosterman/dp/073...
We all used the phrase "selling out" frequently (on the east coast of the US), but I remember one high school friend who invoked it constantly. Calling people "sell outs" (i.e. lacking in authenticity) was a common insult.
Grunge bands and in particular Kurt Cobain had almost a pathological obsession with "selling out", to the point where it had some part in his death. Even popularity was seen as a sign of selling out -- it was better to be true to your indie roots.
There are some interesting quotes in the book from Cobain and contemporaries, and the author talks about influential movies at the time that dealt with the concept.
I was never a Calvin and Hobbes fan, but it's definitely interesting and notable that the creator avoided "selling out".
While I think we were too obsessed with it back then, I think a concept that probably needs more respect today. You could even talk coherently about Google "selling out", although that concept may now be foreign to many people. There was a notion of authenticity and that you cared about the mission, i.e. organizing the world's information. But that is long gone :-(
In retrospect the obsession with "selling out" in the 90's was a reaction to capitalist values affecting more and more parts of life. Though, being a teenager, I didn't realize that, and I just said what my friends said!
It was a way to keep your peers in check. But it's sad that people don't even notice it anymore. They would wonder why you did NOT "sell out".