According to the createspace royalty calculator, a 150 page book printed in full color with bleed would have to be sold at $20 in order to make a profit (just about break even). However, why is it that on Amazon, I see books that are around this length, some possibly 200 pages, yet priced at $10? These books seem to be popular in the rankings. I would like to know how the author makes a profit when the calculator tells us that they should be making a -$5 loss every time they sell a book? Thanks.
They are probably not "print on demand" books. Offset printing is cheaper if you happen to have a huge warehouse to store books in. Alternatively owning your own POD printing business so you can use it at cost.
Failing that, color is just not an economical choice.