> Who tried and convicted him?
This is not a court of law. People have a right to (and do!) form their own opinions without going through the courts. Calling something a scam does not require a legal judgment, AFAIK... unless you want to argue that it would be slander/libelous to do so. However, this would probably be a tough sell since saying "X is a scam" in everyday life would probably be interpreted (for legal purposes) as saying "It is my opinion that X is a scam" and opinions cannot be slander/libelous AFAIK.
> This is cryptography, there is no need to convince people. There is either definitively absolute evidence, or there is not
In theory, but unfortunately not always in the real world.