Buying land owned by another country means diddly. All it takes is one politician or motivated company to declare the contract void, and that happening is merel

Buying land owned by another country means diddly. All it takes is one politician or motivated company to declare the contract void, and that happening is merely a matter of time. You’d need to buy it and split it off as a country and be prepared to defend it as such and pray that the locals are willing to be absorbed by your new government. The cost of that is several magnitudes larger than merely buying land.