'Experts say so' is a fantastic heuristic, which definitely increases the probability of being true.
That depends on the field in question. There are a lot of fields full of "experts" whose predictions are notoriously unreliable.
As opposed to the laymen in those fields?
Related: Heuristics for Evaluating the Soundness of the Academic Mainstream, Admitting to Bias, The Ideological Turing Test