I may be looking at it wrong but there's an odd flaw to me in the premise. I view "pay money to avoid being shocked" as something that is happening to you, out of your control. Pressing the button, regardless of the outcome, is something you are choosing to do and is most likely a result of curiosity and bordem.
I think a better approach would have been "if you push this button, the simulation is over and you loose", and then see what people do.
"And then I saw the fields with my own eyes, watched them liquefy the dead so they could be fed intravenously to the living."