In many projects, staking allows you to participate in governance.
You might also want to stake in order to keep up with inflation. If you make 10% in token interest, but the supply has increased by 20% in the same time period market cap decreased, you've probably lost money overall. You're still better off staking than holding in your wallet.
Point is that staking is not necessarily done as an expectation of profit (regardless of how crypto exchanges might advertise it).