What have we learned after all these years ? After all these sales of zappers all around the world ?
->that there is not 1 objective proof (nothing) that the electric signal produced by a zapper manages to kill parasites (worms) in a human body, and considering that electrodes are put on the palms of the hands and on the soles of the feet, and how current spreads, it most likely disturbs some of these parasites (worms) and make them move to others parts of the body where there is less current (for example, in the head area)
->that after all the reasonable critics of these devices and total lack of objective proof that they help to get rid of parasites (worms), "paralier" (and others similar sellers) never gives up, continues to spread lies/misinterpretations on forums and youtube, even use the name of great people like Royal Rife (even if their tech is different) to improve the image of his devices and to sell more of his (inefficient, useless) products.
->that there is a never ending flow of infected desperate people, who are ignorant, and have no others alternative to try anyway, who are intrigued by this high tech alternative mysterious supra hyper intergalactic futuristic technology, so let them buy the crap, why not, maybe after being scammed a few times, it can help cure their gullibility ?