You have probably misunderstood something, because regular electric bikes stop helping your speed at 25 km/h. If the engine works at a higher speed, it's a light moped, which is a motor vehicle, and needs a driver's license. (I think this is the case in the Netherlands same as where I live).

There is nothing extreme about doing 30 km/h on a free bike path. Fatal accidents may however happen at lower speeds, or even when completely stationary, and a bike helmet reduces the risk by a wide margin - even if the risk is not that huge to begin with.