I've heard various theories on the " gangstalking " theme . One such theory that could answer your question as to how to accomplish such an elaborate scheme on targeted individuals is the belief that it is all run through a supercomputer , and the spirit realms essentially use agents ( who are in human form) who are connected to them via mind control , nano chips , spells etc ... it sounds bizarre, but some people really believe this . I will attach a link to a website I read on this topic soon.

Another theory is that instead of remote control killing the targeted individual . They are keeping them alive for a certain purpose they may have not revealed yet . Some have speculated the reasons range from A-Z and almost anything you can think of . I've heard that they keep some alive and constantly harass them because their victims are a part of a giant "game show" if you will , some say that it all boils down to money and some very sick elitist individuals actually pay top dollar to have this individual watched , harassed and surveilled 24/7.

I've also heard theories that the victims of this either come from very unique bloodlines , have very unique genetic makeup , high IQ's, and have very unique creative, intuitive or psychic abilities .. and thus can be kept alive and harassed until they break and can be turned and used as a government asset .

And there could just be a sadistic reason of wanting to make someone's life agonizing before they are killed for some sick form of pleasure.
I've heard many theories and though they sound bizarre I am convinced " gangstalking" is a real thing that happens daily . With the technology to spy on people now , it makes sense that top notch targets or persons of interest would be watched by those who seek to turn them , extort them , harass them , or murder them .