Without considering the fund's dividend reinvestment, if the monthly investment is 1 0,000 yuan and the annual investment is 1, 200 yuan, the annual average rate of return will reach 1.5%, the principal will be 240,000 after 20 years, and the income will be about 1.2 million, and the principal income will be about 7 million after 30 years. If calculated according to the annual rate of return 10%, the principal income will be about 400,000 after 20 years, and the principal and income will be about 2.2 million after 30 years. Therefore, it can be seen that after retirement, you want to rely on the fund to support the elderly. The longer the investment, the better, and the higher the rate of return. Then, according to this result, see if it is necessary to adjust the principal and time of the fixed investment. After all, the rate of return is beyond our control. Considering human nature, even the rate of return of 10% is not easy to obtain for a long time. However, the more the principal of the fixed investment, the longer the time can make up for the uncertainty of the rate of return.