Corruption isn't a wealth preservation tactic. It's an exploitation tactic.
Whether you're strip mining the earth's resources, stripping away the wealth of the nation, subverting the moral/political culture or simply just amassing ill-gotten gains, corruption is the proven method.
Many places have deep histories and convoluted legal practices, which from an outside perspective gets dismissed as corruption, but internally it is considered due process
The idea that rule of law basically doesn't exist and isn't the method of choice in perpetuating a circumstance in "these other corrupt countries" is overly broad and often inaccurate
Whether you're strip mining the earth's resources, stripping away the wealth of the nation, subverting the moral/political culture or simply just amassing ill-gotten gains, corruption is the proven method.