I write for myself.
You should write for you, unless you prefer an audience. I personally would not want my journal to published, because I am not ready to share my life with the world.
Writing is a way to escape and reflect on all that is bothering you in your life, whether it be about your annoying roommate or the cute guy that fails to notice your existence. Write to help clear your mind or get something off your chest. Confess your secrets to your journal if you do not want to share it with anyone. Writing can be a tool to help get the negativity out of your life or remember the positive events in life.
We all are all getting older every single day. Writing about today and look back on it decades from now. This reminds me of a quote by one my favorite authors, Dr. Seuss, “Sometimes you will never know the value of a moment until it becomes a memory.” Write for you to help you remember your college years or a fun family function.
Write for you. Write to vent, confess, or remember. If you want to be daring then you can even write a story. Writing is beneficial to all in many different ways.