Presumably the same reason they concentrated the current amount in the first place?
I mean, I get being optimistic and all that, but we are talking about people who, once they got enough to live in opulent luxury, for long enough that their descedents would never need to work while still owning yachts, said to themselves "This is not enough, I must get more". And then, when they actuall got more, said "This is not enough, I must get more"... and they haven't stopped trying to get more!
So, what is your belief centered on, that at some point they would stop trying to grab all the resources they can? They didn't stop before, why would they stop now?