What does selling out look like?

I'm trying to figure out if I'm a sell-out or not, or what a sell out actually is.

Some fringe artists seem to believe that any time you get money for doing something, that's selling out. I'm not that anti-anything to fall near this camp. I know another actor who gladly admits to "selling himself out" for any and every commercial over the span of fifteen years. He seems comfortable in his life. Not super famous, but been in pretty much everything as a day player. Is that selling out? Working your craft?

My issue right now is that I got cast in a commercial for a company I do not support. Does this mean I sold out? I'm an extra, so my face probably won't be seen, even if I'm not seen, it doesn't change the fact that I'm still doing it. Is it okay because I'm taking their money, or not okay because I'm taking their money? Work is work, but not all work is created equal. At this point, I'm not doing anything against my personal morals, but yesterday morning I never would have thought of working for them. Ever. Now I apparently will.

All steps to get my own stuff produced, like I am gaining points for doing all these other things, and when I get enough points, I can cash them in for my own project. In that sense, I think the means and the ends are not that different. As of now, I am content in my choice. It does not not change who I am. It does remain an interesting question; what does selling out look like?