That's extremely untenable from a sovereignty and foreign policy standpoint. Most countries do not like it when huge fractions of economic segments or asset classes are owned by foreign interests, and will usually start obstructing efforts through law / regulation / straight-up theft.

Isn't this model pretty much how Costa Rican preserved rainforests were funded?

I get the sovereign state thing, but there are models of engagement, flawed, which are like this. My limited understanding is that its not enough to buy the land: you have to defend it from predation by outsiders/others.

There's probably many many more reasons why it's a bad idea, heh. No need to argue over which one precisely is the best one.

but then you have to hire security and stuff. too expensive.