The article suggests that the S&P 500 index has delivered an average annualized total return of approximately 10% since 1957, and historical data indicates that long-term investment in the index significantly outperforms short-term Treasury bills. Although the current price-to-earnings (P/E) ratio of the S&P 500 (29x) is higher than its average over the past three decades (20-23x), for investors who believe that the top 500 U.S. companies will continue to grow over the coming decades, long-term holding remains a wise strategy.