Some would argue this....
I would say you are a pro if you devote the time needed to be sucessful at the game, and treat it like a busniess.... in todays game there is so much variance, even the best players in the world have losing year.... granted I also believe there needs to be a life time of documented profitable play.... to get this 1 you need to be dedicated to studying, and doing the work off the table. 2 you need to have a proven life time track record in winning, even after a very long downswing that could span a few years. And 3 which I think is the most important part of being able to call yourself a pro. I think you need to be able to make money from the poker industry, not just playing it. Because Varince is a bigger issue now then ever before, you have to know how to make money with poker not just playing it. Might that be through coaching, streaming, YouTube, social media groups, tournament directing, or promotions....
Now let's say you play alot, it consumes almost if not all your free time. Or you try and make a living off of just playing the game. You dont really study outside of just watching a few videos here and there. Or maybe you inspire to make millions off of just playing the game, but dont really put the work in off the table. These are your REGs, they can be good, they can be terrible....
Then you have your REC players, who will show up to a casino not knowing much more then the basics. They really dont care if they win or lose, they just want to have some fun. They might as well put thier money into a slot machine, cause chances are they are just trying to get lucky....