Hire the Third-World, Become the Third-World ...
(media.scored.co)
The problem with caste systems is that they're subject to entropy. All it takes is one lighter person breeding with one darker person to do irreversible damage, and over thousands of years that darkening works its way up to the lightest royalty. It's what happened to the original Indians and it's what happened to Spanish-Mexicans. The only way to prevent the decay is to completely remove darker people from the equation.