Choose a sports car instead of a luxury performance car when the experience of steering, braking, and placing the car matters more to you than passenger space, quietness, and long-distance ease. The strongest reason is a clear preference for a particular driving experience, together with a realistic willingness to live with the chosen car's compromises. It is not a guarantee of greater speed.
The categories overlap: many sports cars are luxurious, and many performance sedans are rewarding to drive. Compare the actual vehicles rather than treating price, body shape, or horsepower as a verdict. A compact two-seat roadster and a refined performance sedan offer different ownership experiences even when both are enjoyable.