Unpredictable things happens at that speed.

Forget about braking distance. The reaction time is the difference between life and dying before you even know it.

I know of one example where a motorcyclist killed himself that way. Nobody knows how fast he was going but it’s assumed above 250 km/h, on a regular highway. Down the road is a cross section. A lorry was fully stopped at the crossing and preparing to turn right onto the highway in the same direction as the motorcycle. The lorry driver checked both directions and saw that the road was completely clear as far as the eye could see, hundreds of meters.

A split second later he heard a bump and pulled over to check if he had hit an animal or something. He found a massive hole in the back and the debris from a motorcycle. There was no brake marks or anything indicating that the motorcycle had even attempted to brake or steer around. The theory is that the motorcyclist might have glimpsed at the speedometer or something for long enough that he drove the entire visible distance before being able to even react.

Obviously he was a fault himself, but the point is that at speeds like this, you no longer have any capability to predict what happens next.

If your friend thinks that cool, he might as well play Russian roulette. At least that doesn’t put innocent people in danger.