I'm gonna add to this discussion and say that anyone can call themselves a professional, and anyone who actually is a professional at something isn't necessarily a competent human being. Someone calling themselves a Grandmaster is not just a completely subjective thing but even if for whatever reason they have achieved Yoda levels of competency in their art, they are still prone to mistakes. Look at John C. Kim, a skilled, widely-heralded martial artist who ended up being a fraud. If you wanna go beyond martial arts, look at Elizabeth Holmes, a highly-educated individual who ended up being probably the most incompetent, dim-witted psychological manipulator in human history. Despite pretending to be a high authority in her field of study, she barely got anywhere before being called out for her rubbish.
This is why I don't like the title "Grandmaster"; it's a pompous, narcissistic way that an ordinary person will use to try to assert themselves above others. The only way that I will respect a highly-proficient individual is if they are humble, doing away with these ridiculous titles, and instead show competency through their actions. The moment someone tries to pull a Snoke on me and refer to themselves as Supreme Grandmaster Ruler Overlord Commander-in-Chief Admiral General Deluxe is the moment I refuse to put any faith or respect in them or anything that they say.