Here’s why: When you withdraw money, it will first come from the interest you earned, not the original amount you invested. This will decrease the overall interest earned, leading to lower returns for a short period of time. However, if you keep your investment, the interest will eventually start building up again, and you'll end up earning an effective interest rate of up to 7/8/9/10% XIRR as per the invested plan over the course of a year.