One of the big questions becomes the money. Not how much but where it comes from. So it seems we are getting a definition here, finally. You see, it really doesn't have anything to do with how much you make. What it has more to do with is whether or not you make enough money playing trumpet that you really don't need to do anything else for a living.
Different people require different amounts of income.
I feel the same way about college professors. So, there's my definition. As you can see, this definition has nothing to do with how good of a player someone is nor how popular they are. This brings me to consider some of my favorite musicians in Houston. I think about Joe Farrera, who is one of my favorite drummers in Houston, but has a serious day job.