It’s interesting that drmabus has a point, though not the one he thinks.
Randi’s already pointed out that the constant need to defend the MDC against throngs of people who think they can just pick out the right card or make a pair of sticks cross over a glass of water and walk off with the money is a contributing factor to his decision. As are the constant rebuttals that must be put out to the very vocal accusations that are made as excuses for why someone did not take/pass the challenge.
Clearly, if any of the loons could demonstrate their ‘gifts’ under controlled conditions they would probably have done so and won the money. It’s the fact that they can only make their ‘powers’ work when there is insufficient care taken against (self)deception that is so telling.
The self-deceiving won’t understand this of course, and either excuse their failures or argue that the controls interfere, the deliberately deceitful will catch on more quickly that their usual trickery is unlikely to pass unnoticed. Hence the cries of fraud are usually loudest from the fraudulent.