I think the reason for this is pretty intuitive: more expensive (NYC/Bay Area) homes are purchased by high income people. And higher incomes are more affected by the stock market because high comps are composed of higher % stock. Someone making 200k might have 20% stock. Someone making 600k might have 50% stock. So a 10% drop in stock market costs the first person 2% of their comp and the second person 5% of their comp.