Speed in a crash isn't a particularly big problem. The dangerous bit is how quickly you decelerate. Going from 100kmh to 0 over a few hundred meters and a few seconds by bouncing around the road and the barriers won't be much fun but you'll walk away. Going from 100kmh to 0 by driving in to something stationary will kill you pretty much instantly unless your car's safety tech saves you by giving you a cushion of air to decelerate in to.
Speeding isn't dangerous. Stopping is.