> It's not much more of a threat to society than a handgun.

These drones could be programmed to target specific groups of people, for example of a certain ethnicity, and attack them almost autonomously. Short range slingshot mechanisms are several orders of magnitude cheaper to build than firearms. Moreover, the inhibition threshold is much lower if you are not involved in first-hand violence. There is also a much lower risk of getting busted and no need for intricate escape planning.