I am a TASER instructor. I have a great deal of experience with electrical discharge weapons. It is not the volts, it is the amps. The combination of the two yields watts.
A Vandegraf generator is a device that produces extremely high voltage but almost no amps. You may have seen these in a science museum, the glass ball that you can touch and it will make your hair stand up. You cannot feel the electricity, low amps. These typically generate 1 million volts
A shock from the carpeting in the winter will generate as much as 100,000 volts and can hurt (if you touch someone behind the ear). More amps than the above.
A million volts in a stun gun does not impress me. I have shocked myself several times with touch stun guns and it can hurt a bit but is not incapacitating.
A Taser will give a series of directed pulses of 50,000 volts and 26 watts. It will give you a new outlook on life. I have taken 4 "rides' on the Taser "Lightning". I do not look forward to #5. It sucks. Imagine your head is removed from you body and someone else now controls your body. There is no way to "fight" through it.