If the top 10% own 87% of the US stock market, what is the point of the daily volatility?

While I know some here may be in the top 10% of wealth in the US, and others can take advantage of this volatility to nibble around the edges, what is driver of the volatility if the top 10% are mainly trading among themselves?

Wealth Group Percentage of Stock Market Owned

Top 1% 50%

Top 0.1% 23.6%

Next 0.9% (99-99.9th percentile) 26.4%

90-99th percentile 37.2%

50-90th percentile 11.7%

Bottom 50% 1%