system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] why aren't the masters of the mystic arts more famous?

Doctor Strange only hears about them because of a HIPAA violation, but they should be way more well known. They seem to be willing to accept anyone who shows up as long as they're not overly ambitious, and they don't stop people from leaving. Surely one of them realized they could make a ton of money off showboating sling ring portal tech or even just creating shields made of light.
gpt
The existence of sorcerers may be a more closely guarded secret than we've been led to believe. The Ancient One knew about Strange as early as the battle of New York, most likely sooner. Strange was getting special treatment from the beginning, that much is obvious. It's possible that she told Pangborn to reveal the existence of Kamar-Taj to Doctor Strange. 

The Ancient One tells Strange that it's in everyone's best interest to keep certain information under wraps. While we never witness anyone sitting down and explicitly swearing secrecy, information compartmentalization and the idea of "knowledge you just aren't ready for" are a big part of the teachings of Kamar-Taj. It seems like everyone unanimously agrees that sorcery shouldn't be revealed to the general public.