This is a great quote from Seth Godin. I highly recommend reading his blog.
Publishing books to make money...
is a little like hanging out in a singles bar if you want to get married.
It might work, but there are way better ways to accomplish your goal.
If you love writing or making music or blogging or any sort of performing art, then do it. Do it with everything you've got. Just don't plan on using it as a shortcut to making a living.
The only people who should plan on making money from writing a book are people who made money on their last book. Everyone else should either be in it for passion, trust, referrals, speaking, consulting, change-making, tenure, connections or joy.