I think autonomous cars are something that must happen, and the sooner the better, but I am also a bit concerned that they could represent the ultimate weapon if a malicious actor gained control over them.

One battery fire isn't a problem, but if every 2nd car in a city or country crashes into something in a way that starts a fire, that becomes a very big problem extremely quickly.

Watch on youtube any video that shows puncturing a cellphone battery what happens. Then scale that up and imagine a scenario where one idiot on drugs drives one in supermarket or mall entrance and the car's battery gets punctured. After that comeback and tell me you still think 100 casualties are hard to happen from only one EV car.