So 0.1% of people who don't have a burning desire for it should still write a book, which seems like a large amount of people to me.

And there's not really a way to know if you're gifted and talented at writing, so just go for it anyways. Your appeal to exception falls flat because there's no reason why there can't be another one.

That's like 3 million missed books in the US alone. I agree with the argument, though. And the number may be reasonable.

You're assuming that 0.1% can still get the thing finished and out there, given a success rate of around 1/100 between people who want to write a book and those that actually complete it, the number of missed books is probably closer to 3000.

0.1% of the US is 300k (and less than 100% of people have considered writing a book).