I continue to ponder the answer to this question, because responses to it are many and varied. Tonight I'll touch on just a couple in addition to what I shared a few days ago.
As blunt as it may sound, I write because I have to write. A day without writing something is a day without joy for me. I never knew that until after retirement and a time when I thought, "I never want to sit in front of a computer again!"
How wrong I was in making that statement. The sitting in front of a computer that I'd been doing for decades was to type pleadings in a case for an attorney, or to draft up some legal document or another; it wasn't writing for the pure joy of it.
Now, I write because I want to, I enjoy it, and yes, I have to write. And now you're next question may be to ask for an explanation of "I have to write."
And the answer to that is that I have a story (perhaps more than one) that either needs to be told or deserves to be told. No one can tell that story but me because it is personal to my life. Others may be the creation of imagination, but they will also be mine to tell.
If I don't write, will they ever be told? Likely not. So, I write. Sometimes every day, and as you can tell from my recent presence here, not always every day.
Do you have a story or stories to tell? Have you started writing them down? It doesn't mean that you're striving for publication, but perhaps just leaving stories for your children and grandchildren to enjoy in the future and pass along to others in the family.
Think about it . . . try it . . . you too may find joy in writing, and then you'll know why I write.