I once spoke to an elderly Hungarian doctor who had treated Papp, talked with him at length in his native language (Hungarian) and had decided he was a flaming nut case.
I have heard that Papp was crazy. However, being crazy does not necessarily preclude being right about something, or being competent in your job. As it happens, I used to know several crazy people because my late aunt ran a halfway house. See:
As you see in these case studies, many of these people were smart, capable, gainfully employed, and reliable experts in what they did. You should never assume that mental illness precludes competence or the ability to contribute to society. Yes, sometimes it does, but sometimes it does not.
I have spoken to several flaming nutcases who believe in cold fusion. The fact that some number of crazy people believe something is not evidence that it is wrong. Many crazy people believe in the conservation of energy, Special Relativity, and much else that I am confident is true.
I suggest you have jumped to conclusions and you are judging the issue based on personality and people rather than technical details.