The Volocopter has a ballistic rescue parachute. A failure of a few of the 18 rotors/engines is not a problem and can be compensated; complete electrical failure (or failure of more than a few) would require deployment of the parachute.

On the other hand, mechanically a multicopter is much simpler than your average heli (rigid rotors, i.e. no collective/cyclic/swashplate/articulation, no anti-torque, no gearbox, etc.) - so I'm wondering what the relative safety turns out to be.