[Moonman62]

You appear to be glossing over the fact that people with that much in their wallet tend to be more skepitical than the average bear.

Not always.

Is it a 'magic box' or a high-tech hoax?

[editor-surveyor]

>> “Is it a ‘magic box’ or a high-tech hoax?” <<

.
Or neither.

The inventor would have to be a fool to reveal even a shred of the physics to the non-paying observers (us).

Perhaps he is in the dark himself too, as to the physics, but has some concrete observations on the behavior of his “fuel” that are reliable within the range in which he has so far operated.