Can you give a cite to any statistics or resources that suggest that real estate fully explains the wealth gap? The ultra-wealthy tend to have much higher perc

Can you give a cite to any statistics or resources that suggest that real estate fully explains the wealth gap? The ultra-wealthy tend to have much higher percentage of their assets in securities than real estate. So that real estate explains the entire wealth gap sounds curious, although perhaps not impossible. I just have no idea how that could be.