Everyone is missing the point, this is an example of money laundering 1. Get dirty cash from drug sales, prostitution, etc and buy amazon.com giftcards in shops in US 2. Input the codes into various amazon buyer account(s) 3. Buy the book(s) from these account(s) 4. Amazon takes a cut and pays clean money into authors bank account.
The best? Amazon takes a 30% cut and then the government (here in the US) takes another 28% for income tax, 12.4% for SSN, and 2.9% for Medicare. You get less than half your cash into clean money. Plus, there's a huge paper trail of buyers and the million dollar book would likely set off flags on every sale.
Losing ~20% is not too bad when clean money from a reputable source arrives in your bank account, if you are reselling lets say hard drives or phones.