Instead of trying to follow the success of someone else, learn how to make your successes matter more. One thing the book mentioned is to treat your book like merchandise; something you haven't dictated your heart-and-soul into. If your job was to sell tires, you would work out a pitch, a way to attract people who are in need of your product.
Well, your book is your product. So figure out how you want to sell it to your 'customers'. It doesn't have to be a trend or popular genre, you just have to make it seem interesting and desirable.
And yes, I know that's a lot easier said than done; I'm still working on my own pitches and techniques. I don't claim to be an expert in the art of sales. But I want to discourage writing trendy subjects for the sake of profit. If your passion tends to fall into that trend, go for it! If it doesn't, you just have to work harder to see the results of your time.
I find it easier to detach myself from my book by breaking my project into two milestones:
Finishing the Manuscript
Or, in other terms, getting your book to the point it's ready to go on the shelves. Where it would be ready for a publisher to print and start selling. No marketing, or thoughts of marketing, are in my head during the journey to this end goal. All I want to do is pour my heart-and-soul into getting this written and ready to go!
Bringing in the Big Bucks
Or little bucks, or just something to get me coffee in the morning. It's not 100% profit at first, not until a name is out there that people know and 'trust.' But now that your book is ready and rearin' to go, pick your poison. Are you going through traditional publishers, or are you going to rough it yourself? With e-books, this has become much easier than in the past, but there's still plenty of work to be done. Focus your time and energy into selling your book (and yourself) to readers who yearn for what you have to offer them. They won't be camped outside your door, green bills in hand and waving towards you, so get out there and find them!
I'll be writing more on tips and tricks I'm discovering to find those elusive readers. It doesn't help that my two niche's are rather... unpopular. But it's work that I go to bed at night with a smile, because the journey to my second milestone is fueled by the first one: Pleasure.