What you believe to be the best reason for a playwright to create a play?

There are a number of reasons to write a play, including:

1. The money you can make from selling or renting the script.

2. The satisfaction of seeing your name on a book or poster.

3. Creating Propaganda for a cause you believe in.

4. Helping acting companies who need a script (could be your own acting company)

5. Seeing how a skilled actor can realize your ideas.

6. The sheer joy of creating something that did not exist before.

As to which is "best", ideas probably differ from person to person.