playwrights
Playwrights are compensated from theatre ticket sales. Which means that your audience is always going to be a lot smaller than the audience of a film.
Theatre is very easy to break into. Since it doesn't cost much to produce a staged production, places like NY will have theatres that stage dozens of productions a year. A good play which receives rave reviews can cost only a few thousand to produce. An indie film, by comparasion, costs somewhere between hundreds of thousands to 12 million dollars to produce.
An organization good at writing grants or that has made money off of previous production can easily produce a play inhouse without going to outside investors (unlike film). The economics of theatre are entirely different. Also, plays generally don't spend millions of dollars in advertising, seldom have to attract big name stars (with the exception of very big broadway production), don't have to have big name directors, don't need special effects, equipment costs are less, barriers to distribution are non existant, etc.
Every theatre company I know off does not require an agent to submit stageplays (maybe a few Broadway productions might be the sole exceptions).
Of course, a big percentage of playwrights have other sources of income.
But that's not the point. Playwrighting is one of the easiest forms of writing to break into, and is much easier to break into than screenwriting.