I can’t imagine my father ever calling himself a “professional University lecturer” or my brother referring himself to as a “professional math teacher”.
The word professional means many things; but when it’s followed with a vocation, such as “photographer”, it doesn’t mean that you enjoy photography a lot, or that you speak politely about it, or that someone bought a print from you. It doesn’t even mean that you have a website. It doesn’t mean you teach workshops and lead tours, either.
Show me a professional photographer, and I’ll wager a dollar I’ll show you someone who’s struggled to pay their rent, who’s sold gear to make their car payment (or sold their car to make their gear payment), someone who’s eaten peanut butter sandwiches because that’s what was available to eat.
A professional photographer has made real sacrifice to do what they do (there are always exceptional cases, with trust funds, a wealthy spouse, etc). It’s a risk. It’s giving up an awful lot to choose to pursue a particular vocation. It’s losing on that risk, picking up, and swinging the stick again. And again. And yet again. Repeat, infinitum.
It sounds much more glamorous than it might be. It means you take the bus sometimes, it means you sit in the rain and wish you were somewhere else. It means you sometimes take a lower price for a sale because you need shoes. Pardon my French, but it means you’ve been sh** on. It means you’ve wished, cursed and swore that you had chosen some other manner to live by. It means you say ‘yes’ when you think ‘oh sh**, that gig sounds like hell’. It means you say ‘yes’ and then that gig actually IS hell. And you then say ‘yes’ again. Still you pursue it.