It's actually a device to... It makes the air... It's for... I could explain, but you wouldn't understand :)

I assume they accept it as part of the sport and an acceptable risk. If they don't like it some other company will want their name on the car.

This is true, and it brings their car into the spotlight if they weren't doing well before. 5 minutes of coverage with a car with your logo on it is way more valuable than a 15 or 30 second commercial.

it's to slightly increase high-speed downforce, every bit counts on an F1 car