It's hard to say if you decide to invest in 800 yuan every month. After three years, you may make a profit or lose money. If you can predict whether you will make a profit or lose money in three years, then everyone will become rich. Assuming that the average annual income in these three years is about 10%, the 28,800 yuan invested after three years will have about 20% income. If the average annual income in these three years is about negative 10%, the 18000 yuan invested after three years will probably lose about 15%.

Although the fixed investment of the fund can better stabilize the investment cost of each period, its contribution to the income is only a small part, mainly depending on the invested funds and market trends.