what compels people to write?

because they can , and need to pass along some part of their own energy or thought process, at first i would say it was used as a way to communicate the legends and story's they had no language for as yet.

now days some write for the pleasure of it the art,some write because they are frustrated and want to be heard

some to entertain some to educate some to enlighten and some to deface or exert control over an others surroundings even their own .school books are randomly scribbled over .

Often the abstract mind takes over when you are on the phone nd you begin to doodle on paper .

its a natural instinct seemingly. Give a baby a large crayon and after trying to eat it he/she will happily amuse themselves drawing over everything

believe me i know this to be true lol

IMHO I think Writing is one of the nearest ways, either to heart or to mind for expressing, either feelings or thoughts.

I think the basic idea behind this i self -projection in some way or the other

First of all to express their feelings in private,secondly to find any takers for it and thirdly to quich their thirst.

Writing is real expression of mind in its good sense and in wrong sense to hide everything in mind.

the desire to be remembered, to leave a legacy, to send a message to someone else they have never and likely will never meet in person. to say "I existed, and I matter."