How long do you think he would still be breathing unassisted if he accepted 40M from someone for a scam? Think he would make it for an entire week?
A great many scams have been pulled in the world involving losses far greater than 40M, with the perpetrators going unpunished.
It depends on what sort of organization the perpetrator has to protect them. If it is a version of the Russian mafia, I am pretty sure they could get away with it. It is also possible to protect yourself to an extent by careful selection of the victims. If you make sure the victims are vulnerable to intimidation themselves, it could work. Some victims will not wish to be identified.
There are places in the world where it is nearly impossible to reach someone with either legal or extra-legal force.
The fact that Mr. Rossi would not take $200,000 from you certainly is interesting. It says to me that there is no reason to be very excited about it, because I have no way to act on it if I knew it was valid.
I hope that the device produces energy as advertised. We should know by the end of the year. If there are no independently owned working models by that time, We can be pretty certain that it is a scam.
If his invention does work, I'll bet this picture will rapidly change.
What impressed me about him is that he wasn't interested in outside investors, at all. Never asked to read the restrictions on my offer, just a polite, "No, thank you."