Yes that's true, but the actual percentage of ownership hasn't changed, it stays the same. But the bigger issue is that the economy is not really a finite thing. Owning a certain amount of land, maybe by inheritance is not the same as owning a never changing percentage of all the resources. A good counter example might be something like inheriting shares of Google, or Amazon. Those people might never have owned any significant percentage of land but that did not stop them from owning something else that is more valuable than the land. So the resources change over time and I don't really see why land ownership is being used as a proxy for everything. Now, also, you may have not been making that point yourself but just clarifying. I just want to talk people down from the land confiscation movement because it seems destructive and pointless.
