I didn't "need" $90k to write the book.
I chose to sell copies of a book, at typical book prices. Thousands of people chose to buy the book. That's where the $90k number comes from.
> And the book's photos are black & white ...
"The food is terrible...and the portions are so small".
The wonderful thing about the free market is that those who want to buy a thing can, and those who don't, need not.
Cheers!