Who IS a "professional"?

I subscribe to very few blogs and today an article was posted on what may be my favorite, and it got me thinking. The following started as a reply, but I decided it might be appropriate here too.

In the last couple years, I've been forced to reevaluate myself in light of my career. I've spent nearly 2 decades in software in one form or another and despite being able to make some pretty hefty claims; they always sounded exaggerated to my own ears, when coming out of my mouth so I felt awkward calling myself a professional even though I can't imagine many people refuting the claim. Still, I was reluctant to claim the title until my personal interest in virtual reality, backed by my years of photography and a years of "playing around" with a variety of video technologies saw me into the role of CTO in an up-and-coming VR company which in turn found me working side-by-side with (not employed by or for to be clear) the production team for RedBull, with the streaming engineers they use to broadcast to the Internet, and helping Samsung give 1,000's their first experience with VR at the largest music festivals in North America. 

This article [https://houldsworth.wordpress.com/2016/01/26/what-makes-a-professional] resonates with me because by most objective definitions, I'm a professional software developer and DBA, but I didn't feel like it and few labeled me as such who had the knowledge and experience to do so (worth mentioning that I work from home and am not even surrounded by co-workers or peers often in that field). On the other hand, I'm quite new to the "professional" field of photography, videography and VR, yet I don't mind saying that I'm one of very few people in the world who has done a real-time video production broadcasting to VR and I've been complimented by some rather significant people in the industry both explicitly and implicitly and a large part of that comes down to the fact that we show up to do what we do amongst 10k's of people, have to deal with incredible challenges on the fly and have yet to fail.

Am I more of a "professional" for having spent decades in a field, or for successfully doing something new and difficult? I think you raise a great point and I'm presently of the mind that I am on both accounts, but for very different reasons in each field. In the end, not even others with experience in these fields; paid or not, could do what I do readily (and for pay) and that seems like a good basis to label me a professional in general and in those fields. It does not mean that others are not are not either though, so where do we stop applying the label OR is the label possibly less meaningful in this world where knowledge and experience are such different beasts?

Was Einstein a professional in physics when he was a "only" a patent clerk, but generating his Theory of Relativity, or did he not earn that title until he quit and started receiving funding and/or recognition for that theory?

Is a soldier a professional right after boot-camp, or not until he's fought in a war [and killed an enemy?]