My reading of the results is that your optimized portfolio is not very informative. It shows a corner solution. Imagine US equity return assumption to be 0.2% higher and real estate return assumption to be 0.2% lower, then the portfolio would most likely invest 25% in US equities and nothing in real estate. Bottom line: be careful to draw any conclusions from poorly designed optimizations that are highly sensitive to input facors.
My reading of the results is that your optimized portfolio is not very informative. It shows a corner solution. Imagine US equity return assumption to be 0.2% higher and real estate return assumption to be 0.2% lower, then the portfolio would most likely invest 25% in US equities and nothing in real estate. Bottom line: be careful to draw any conclusions from poorly designed optimizations that are highly sensitive to input facors.