Rihanna is absolutely the biggest hitmaker of the last 20 years but she's had tons and tons of flops.
If It's Lovin that You Want, We Ride, Rockstar 101, California King Bed, You Da One, Talk That Talk, Right Now, What Now, American Oxygen

, Kiss It Better
She's been less consistent than Madonna was for her first decade and a half, and she hasn't had a Top 5 hit on pop radio as a lead artist since "Stay", so what's keeping her afloat right now really is streaming.