“Most of my clients are busy professionals. These people simply don’t have the time it takes to go out and get all the books, read them all, develop a campaign, learn the rules well enough to run a game and so on,” says Dempsey. “It’s much easier for them to just pay someone else to do it. I show up, I unpack my stuff, we play a game, they pay me, I pack up my stuff again and I leave. It’s very convenient for the clients, which I think is a big part of the appeal for them.”
Gaming, even tabletop games, is becoming a paying business more and more…
See http://www.glixel.com/news/meet-the-dd-players-who-make-a-living-running-games-w479506 
Meet the ‘Dungeons & Dragons’ Players Who Make a Living Running Games
For some, a professional dungeon master can be the difference between a fun time and a boring slog through a fantasy landscape