It's wrong to violate human rights.
King Bob needs to attract more tourists to his country.
King Bob wants to built a world wonder.
King Bob uses an army of paid laborers to get the wonder built quickly.
King Bob uses an army of slaves to get the wonder built quickly.
Tourists the world over arrive to see the amazing construction and drastically ups the GDP of Bob's country.
The wonder attracts some tourists but many nations aren't keen on how it was built.