Minnowbooster calculates like this.

If you delegate 2000 SP they multiply that with 10 so that means they get 20000 SP and they pay the value of 20000 SP which is currently around 0.45 USD

If they were paying 2 SBD per day for 2000 SP then I would have delegated my 6000 SP to them. I could have easily gotten 42 SBD a week/ 168 SBD a Month just doing nothing.