1, transaction cost. You have to pay for buying and selling stocks and funds. One person charges for trading, and people in a province charge more for trading. Especially in a bull market. Many knowledgeable people directly buy brokerage stocks. Because it's a definite bet.
2. Acting for financial management. Securities companies will act as agents for some financial products. When investors buy, securities companies make money. More people buy, more natural income.
There are tens of billions of transactions in the stock market every day, and there are also many expenses incurred by the transactions. So securities companies make a lot of money.