The downside is that most countries tax the everliving fuck out of you for owning international property.
If you live in one that doesn't work that way (or, better still, one that allows you to use this international land as a sort of tax shelter), you're good to go.
In summary, the first step to making a lot of money is knowing the rules of the game you're playing. It's worth noting that the rules are subject to change and may be circumvented with great success in certain cases. Consult a good lawyer for details.
I do deeply enjoy Sim City.
But part of that is my desire to watch millions suffer.