True, but you have to consider the market. Which means considering what others want. Writing for yourself is the most beautiful, pure, joyful experience. But don't expect to make any money from it. Take the Nordic crime fiction stories out (Girl With A Dragon Tattoo bla bla). They are written to be bought.
It's a very true sentiment that seems to have happened naturally for me. You could call it selfish or self-indulgent I guess but I usually write when something is bothering me and that tends to show itself. The interesting thing is that although something may be deeply personal or significant for you it can also be relevant for someone you don't know... so yes, we do write for ourselves but the beautiful thing is that in doing so we find each other.