Are well-publicized public demonstrations of psychic ability interfered with by sinister forces to make the would-be psychics fail?

Here you have hit on the reason why all such public demonstrations, with promises of reward and a guarantee of public humiliation if the would-be psychic fails, have not heretofore allowed a convincing demonstration on the part of anyone professing to have psychic gifts. The interlopers cannot simply help themselves in wanting to pull the rug out from under such individuals and discredit them. Not only do they enjoy doing such things, they know full well that psychic ability allows humans to see their secrets at times so they will vigorously oppose and undermine implementation of psychic abilities for any worthwhile endeavor, and especially a public demonstration that might convince skeptics once and for all they wish to avoid if at all possible. They want people to disbelieve because it will be all the more easy to mislead people if such perceptions are discredited and not utilized as a result.