[fiblye]

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.

[TearsInTheRain]

Eh, even nations can't just declare contracts void without serious repercussions. Nations have credit ratings too and frequently utilize international financing

[jhrmnn]

But that goes full circle back to the repercussions criticized by OP.