>>535789874
The only requirement to being a pro is to pass the "pro test," do an interview, and pay your membership fees on time. There are a lot of pros out there at the lower levels that are Expert/Master. Being a pro in the lower rungs of an organization is a part time thing, the tournaments only run 6 months out of the year.
The pro test itself isn't particularly difficult either, it's mostly testing if you know how the game plays and the rules of that particular organization. A big part of the tests (according to Jenn) is the scoring section which includes a bunch of "trick" questions like pic attached. There's other sections like gyakuten scoring, shanten counting, tournament protocol, etc. but you get the general gist.
https://www.youtube.com/watch?v=uLgfOLCIQTA