BCCL
It is true for some people, not all.
For example, retired folks who do not want to lock up their money for 10-15 years or need regular returns to stay liquid, fixed deposits are still the go-to option.
While it is true that fixed deposits (FDs) give lower returns than any other investment product, all other investment products do not give stable returns all the time compared to FDs. Equities will give you more returns when markets are doing good and might even give you zero or negative returns when markets are bad.
Not to forget, several mutual fund schemes offer attractive commissions to distributors for recommending them to investors.
Fixed interest rates do not tend to go up and down frequently. Even if you choose to invest in stocks, it is wise to invest a portion of your savings in a fixed deposit. It puts safety first.