Three years in 3000 is a month 108000. If you are optimistic, you can get 20W; if you are pessimistic, you can only get 8W. To put it bluntly, stock funds indirectly invest in stocks. In order to reduce the non-systematic risk, funds buy a variety of stocks, so the income of stock funds follows the stock market.

The way you invest in funds is probably to save money, so I suggest you invest in money funds and bond funds with low risk every month, and invest in stock funds or stocks in moderation.