If cold fusion worked the way it’s proponents claim it already did we would have as evidence some dead scientists and/or smoking craters. If you are claiming you released those amounts of energies it must have some observable physical effect or it is not what physicists and engineers would call energy.
As of this time and after decades no devices used by scam artists trying to attract investors has been independently verified to successfully generate more electricity than what has been input. It really has turned into a bad joke. But the potential rewards are so great that it is difficult to completely disregard it. Just because charlatans have taken advantage of people claiming their devices do something that they do not... does not mean that the concept is completely without merit.