Over the past 10 years, the average investor in the SPDR S&P 500 ETF Trust (SPY) has not achieved the same returns as the actual index. This is often due to behavioral factors like poor market timing, panic selling during downturns, and re-entering the market late during recoveries. The S&P 500 itself, which SPY tracks, has delivered strong returns historically, but the average investor tends to underperform due to these behavioral biases.
For example, while the S&P 500 has returned about 10-12% annually on average over the past decade, studies from firms like Dalbar have shown that the average equity fund investor typically earns significantly less, often around 3-6% annually, because of frequent trading and mistiming market moves. 投資spy 解決了diversification 的問題，但沒有解決fear/greed 引發的 market timing 問題。能抗拒fear/greed, 完全不考慮市場timing 的定投，也是不容易做到的。
