It is obvious that you know only enough about electricity/electronics to make nonsensical statements. I've been an electronics technician since 1997 and do know what I am talking about. Listen and learn.
Voltage is lost across the skin, not current. The same amount of current that flows through the skin also flows through the blood in the arteries.
These blood electrifiers can supply enough voltage to burn the skin and provide 5 times more current than is needed. That is why they are adjustable so that you can adjust the current to where you almost feel it. If you feel the current then you applying too much and risk burning the skin.