What is a "Professional" Writer?

What is a "professional" writer?

This came up at Metataxu Cafe. A question in the profile:
What is your profession?

They give you a menu... but only one choice... from a list.

Teacher/writer?

Nope. One or the other.

So I ask, how can I claim to be a "professional writer"... if I don't earn my living by writing?

...what about Kafka? What was he?
Certainly there's more to this than earned income.

And what's wrong with being an amateur--one who writes out of love and need?

A professional, at least, can say... I'm no dilettante.

And is there an advantage to being an amateur?

That one's easy. No one can call you a who...ahem... "hack".

Then...what is a dilettante, but a professional amateur?

And what is a hack, but an dilettante... who does it for money?

Like Camus said, let us be neither

... victims
... nor executioners.