My problem with "writing to market"

One of the most common pieces of advice I hear for indie publishing is “write to market.” This means writing your book with an intended audience in mind so you can sell to them. This is sound business advice. Companies that fulfill a market demand tend to make a lot of money. However, there is a fundamental flaw: you’re not writing the book you want to write. If you want to write a book with a unique angle (for example, a zombie apocalypse book set during an alien invasion in 14th century Peru),