I think that the involvement of Defkalion is really quite clever.If you assume that there are no working devices, I could see this playing out as follows:
Rossi and Defkalion are secretly working together. They are each collecting money from investors who must agree to strict non-disclosure contracts, so they can't blab and ruin the scam.
Meanwhile, Rossi and Defkalion start suing each other over various matters. They then use the lawsuits as an excuse to not actually deliver any devices.
They keep collecting investor's money and keep up the lawsuits as long as practical, then they shut down their operation and fade into the woodwork.
The investors believe that all their money was "wasted" on the lawsuits and wander off to find another scheme in which to invest.
The secret to a successful scam is to take the victim's money without letting the victim even know that they've been scammed.
Yes. And on top of that, the victim won't even be certain who lost their money. Defkalion will claim that it had rights to Rossi's invention and were unsuccessful at stealing it. Rossi will claim that his results were encouraging but that for reasons not understood he can no longer demonstrate the effect. I'm sure that he will be very dedicated in trying to reproduce his early "successes".