Yes. We can’t always 100% write about what we want. Well, we can, but not if we want our writing to spread past our inner circle.
I do believe that it’s possible to keep true to your message without selling out. Sometimes we can do that with our stories. But most of the time, “selling” our writing to others comes down to delivering more of what they want to read but doing it in the powerful way only we can.
The trick, as you said, is merging between what you want to write and what others want to read. The important thing to remember is that we can still be authentic when we do this, because we all have our own unique experiences, and the more we can infuse ourselves into our work, the more powerful it will be.
I guess a better way to put it is that we don’t need to become less authentic, we just need to become more selfless. And we need to write for others just as much as we write for ourselves.