Not sure what he’s doing musically now-a-days, but, I think I would still consider Jeff “The Skunk” Baxter a professional musician. Bobby Colomby? I think so too!Yes, several good posts already.
This discussion seems to crop up regularly.
My personal definition is simple and basic. If your main income is derived from making music, you are a professional.
If you earn money a few days a month, while making most of your income from plumbing, or real estate etc - you are not a professional musician.
As to the usual follow on debate.
Yes, there are many thousands of musicians who are NOT professional but may perform better than professionals, maybe highly skilled, important and innovative. It may be for whatever reason they don't want to make music their career.
If you can barely play, are lazy, difficult to deal with and a plagiarist, BUT all your income is derived from playing music, you are STILL a professional musician.