>> Land is expensive to protect.

So you use your wealth to ensure that local authorities protect your interests. You setup people in power, vassal kings, to protect land interests above all others. Who is in charge now? Who are their friends? Do they own property scattered all over the globe? Do any of them care about a box of gold?

Again, as the previous poster suggested, in the past it didn't work so well. The local authorities might want to own your land too, and you will clearly not pay more for its protection than it is worth. There's no need to theorize when the history provides so many examples of wealthy people losing their vast land holdings as a result of change in the political climate.