...but they also laughed at Bozo the Clown.
A fallacy; where the speaker, when confronted with expert opinion/testimony that opposes his point, asserts that the "experts" are in an fact wrong. Einstein is often replaced with any number of other visionaries who were derided by their contemporaries but ultimately vindicated (Tesla, the Wright brothers, Gallileo, etc.) Often a form of AdHominem, as the reason for the experts being wrong is one of:
"They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown."
Carl Sagan
Nazi Germany published a book titled something like "50 scientists against Einstein".
Einstein responded "Why 50? If I was wrong, 1 would be enough."
It was called 100 authors against Einstein. Only one of them was a physicist, and three more were mathematicians. Also, it was published in 1931, so not in Nazi Germany.
Opposite, sort of, of AdVerecundiam. Similar to EveryoneHasHisOpinion
See also: DismissalOfSubjectExperts