someone's portfolio, it's the idea that 20% IRR (on the RE portion) is a prudent return assumption. The reason this is important is because 1% difference in overall portfolio returns (over time) will make a significant difference in someone's overall net worth. The more people with unrealistic expectations, the worse their (eventual) retirement will be.

If you believe that RE can earn you a 20% IRR, more power to you, unfortunately the data doesn't support that assertion.