When many people buy index funds, the most agonizing question is: Is now the peak? Should I wait for a pullback? What if I buy at the top and get stuck? This concern is very normal. After all, no one wants to buy at the peak. So let's think with a worst-case scenario mindset: If someone has unbelievably bad luck, buying at the Nasdaq's annual peak every year for 20 consecutive years, what would be the result? Assuming an annual investment of $20,000, continuously invested for 20 years. The total principal is $400,000. The buying rule is extremely "unlucky": not buying at the annual low, not buying at the annual average price, nor using monthly dollar-cost averaging to smooth out costs...