Even if you have electric flying helicopters, the rotary component makes them very expensive to maintain as blades and components need to be replaced sometimes every 500 hours or less and require constant safety checks and inspections.

Great data, now what's the equivalent for small scale electric motor based helicopters? Considering you're essentially talking about the maintenance requirements of chemical powerplants and rotor wings lifting 10+ times the weight. That's like saying because you have to do pre-operational checks on semi trucks during your trip that it's too expensive to drive cars.

Imagine how many taxi cabs have a malfunction of some sort every year. Now imagine that taxi cab crashing into a building or crowded street if it had a malfunction instead of just cruising to a halt on the side of the road.

Do you not realize we already have thousands of aircraft flying that this could already happen to? It's really strange to have you guys cherry picking this as a thing to be concerned about when aircraft that could fall out of the sky are already over your head right now.

Redundancy is the name of the game, if you have more than the amount of engines you require, then you can have a couple fail and still remain airborne. It's also why VTOL designs are safer as they have some lift potential even with a dead-stick scenario.