Let's assume people are going at a speed that the road is designed to handle, since that's usually the case. In that situation, the behavior you're calling out as unsafe is simply "going faster". Now, in a technical sense that's true, but it's always true. Going faster reduces safety when you're above the speed limit. Going faster reduces safety when you're at the speed limit. Going faster reduces safety when you're below the speed limit.
If you reduce safety to black and white, then you should always go slower, until you're barely moving. If the speed limit is 40, that doesn't magically make it safe to go 40.
Black and white thinking leads to a bad conclusion, so let's add nuance back in. Speed is dangerous but roads are designed to let you go a certain speed while minimizing the danger. You're not being dangerous until you go over that speed. And that speed is almost always higher than the speed limit, especially in good weather.
Going over the speed limit is not itself a problem. It's going over the design speed of the road that's a problem.