My perspective and take on the question is that it depends:
1) what is the primary purpose that drives the writer to write?
2) what is the writer's goal?
3) what is writing to the writer?
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Primary Purpose:
In my functional and operational approach to the definition of purpose, I see our primary purpose as our natural functional responsibility and operational contributions to complement and complete the entire system of life operations.

So, if one's call is writing and he/she chooses not to write he/she is shortchanging the system of operations and his/her life. He/she will never be fulfilled in life even though he/she might be seen by others as successful.
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The Writer's Goal:

If the writer's goal is to make money, once there is no money to make, he/she will cease to write.

Writers whose primary purposes and goals are driven by the dictates of the market will not continue as soon as the market condition is not favorable or fair to them.

What is Writing to the Writer:

This point dwells on whether writing is seen as a legacy tool or a landmark tool to document and transfer knowledge; is writing a professional calling to the writer because every teacher and lecturer of all classes must, in one way or another, write? This class of writers is not writing because they are passionate about writing but because they are obligated to write.
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#Ginuschuks