I have had 10+ people whiz past me at 20 MPH, within inches of my body. Had I taken a step to the side they were riding, I would have been hit and been pushed to the ground. Had I hit my head, I could have died. People die from head injuries all the time. In the shower, falling down, etc.
Yes, I call this extremely dangerous, because death could result.
Is it likely? No. Is it possible? Yes.
A few years ago a 20 something year old girl was walking in SF and was hit by a bicycle, knocked to the ground and hit her head. She died at the scene. (She was in the crosswalk and the rider was charged with something, I forget.) So, it does happen.
