Authenticity in Writing

I had someone post on Facebook, saying they had a concept for a series of books. They wanted to know, if they wrote these books, if we thought they would sell.

This was my response:

"That sounds really inventive, and unlike anything I've seen in recent years. However, as an indie author, I'm against writing a book because you 'think it will sell.' I have to write books for myself, without the thought of 'if I write it this way, will it sell?'

I write it in whatever way it occurs to me, or else the story isn't really authentically me. I want to stand by whatever I write. Do I wanna quit my day job and just write passionately and sell thousands of books? Absolutely. But I try to keep in mind that isn't the reason I write, either.

Should you write the books? Absolutely. But do it for yourself first and foremost and I think you will be much happier with the outcome."

What do you think? Do you agree?