This is a case where huge geo-political actors had a motive to create what would be the biggest con in history - The Allies needed an excuse for destroying Germany. The UK Ministry for War Propaganda, The US Gov, Soviet Gov, Jewish International lobby. All of these were fabricated if they wanted to.
There have been many fraudulent Holocaust survivor claims - before Herman Rosenblat admitted it was 'real in his head', was his testimony proof of the realness of his Holocaust story? How is this different than the other testimonies. Extraordinary claims require extraordinary evidence.