For example, are the crop of country artists, especially the guys classified as "bro country" sellouts or have they found a successful formula and are simply riding the wave and making money like any other good businessman would do regardless of the line of business?
Herb, if they hate what they are doing, then yes, they are sellouts. If it's people who spent their whole life taking smack about how country music is nothing but musicians who aren't good enough to play rock, and then they play country music because it's the current money making rage, then yes, they have sold out. When money is your ONLY, and that is key that you notice the word ONLY, motivation for playing to the point that you play music that you despise so much that you don't even like hearing it by accident on the grocery store Muzak feed, you have sold out. Like today, I accidentally got some Stevie Nicks in my ears. Though with that voice like a sheep, she DID make me hungry for lamb....
I give much credit to bands who stick with their dream and play original music for the door. Those are the players who are truly in it for the music. I will go see THAT band before I go see one of those bands that plays the same 45 songs as every other band.
Also know that this is situational, too. As an old man I think differently than I did when I was young. As someone who does not make a living with music, I think differently than those who do. If you love what you are doing, and don't grouse about moving equipment in and out of bars every night, loading in and out of your car, out of your car into your house.... god bless you. When I stopped not grousing about that stuff, that's when music became a job and I didn't like it anymore. To continue past that point, I would have considered myself to be a sellout.
In an earlier post, I made mention of how people can sell out in every aspect of life. When I married the 3rd wife, I did it because she was somewhat of a local celebrity that made a lot of money and had a nice home. She was the meanest human being I have known in a life that will have lasted 64 years in 2 weeks. I took her abuse for 4 1/2 years. Then I realized that I had sold out and didn't like myself. I knew how to fix that, which moved me on to why I now call her ex wife #3. You have to be happy and comfortable in your own skin. I was not.
Usual disclaimer. This is my opinion. You are allowed to have yours just like I am allowed to have mine.