The estate tax wasn't even enacted until 1916 so there wasn't a period of time where "estates would shrink over time" (for tax reasons, at least; the two World

The estate tax wasn't even enacted until 1916 so there wasn't a period of time where "estates would shrink over time" (for tax reasons, at least; the two World Wars plus inflation actually existing did lead to huge changes in the wealth distribution). And by the early 20th century land was no longer the single dominant form of capital in the portfolios of the wealthiest individuals.