I modified a script for the stage a few years ago then went looking for backers. Here's what I learned....
Costumes - only a very few companies can make costumes for Broadway shows, all union shops.
Stage sets - only two companies allowed - both union.
Musicians - union contracts mandate a minimum of nine musicians per performance, even if there is no music (as with Waiting for Godot).
Electricians - one gets paid to do nothing but press the button that raises the curtain.
It is nearly impossible to break even, let alone make a profit. That is why deep pocket companies like Disney are almost running the game now.
George Cohan Hated Unions.