Talk to theater professionals. Actors in your favorite musicals on Broadway? $1500 a week, if they're ensemble. Don't forget that ensembles have gotten smaller and smaller, but numbers and productions have gotten bigger and bigger. So forget that this means there's also a smaller pool of jobs at this rate for people to get. Most shows have 7 or 8 people in their ensemble who fill in every backround role and are very likely the understudy for someone else. That means, on top of doing the main role they perform (which is very likely the equivalent of singing your way through a 2 hour HITT workout 8 times a week) they also know and can drop everything and perform someone else's part.
Now think of those working off-broadway. At the lowest tier of theater, an actor may make $500 a week. At the highest, $1200.
Now you're probably thinking, well certainly Daniel Radcliffe didn't make $1200 a week when he was in Privacy at The Public, or in Equus on Broadway. Certainly Zachary Quinto gets more money when he does a show at MCC. Of course. He has an agent and buying power that allows him to negotiate. Most actors don't have that kind of buying power, but they have a small amount of ability to negotiate. As do Designers and Directors.
Stage Managers, however, who are not protected by the stage hand's union, but instead the actor's union (this is very important) have no negotiating power and most shows employ 3 people in this position (AT THE MOST) off-broadway. On Broadway there may be 4 or 5.
I have been working in theater professionally as a Stage Manager, on and off-broadway and on international tours for 15 years. I've successfully negotiated a wage above minimum ONCE and it was because my boss died while we were touring in Japan and I was the only person who could do the job. I still had to actually tender a resignation first.
I'm not saying all this for some kind of "oh woe is me, I'm much worse off than Patrick Klepek." What I'm saying is: The entertainment industry is shit, and nine times out of ten, the people you think are making money aren't and instead are being exploited for doing the work they love and making producers money.