A mastermind group for content creators...

...is defined as "a bunch of like-minded creators who connect on a regular basis and support each other in reaching their content creation goals." - Clément Bourcart

In Clément's opinion, belonging to such a group is important for leveling up you content creation as, to quote Darren Hardy:

“According to research by social psychologist Dr. David McClelland of Harvard, [the people you habitually associate with] determine as much as 95 percent of your success or failure in life.”