Cherished falsehoods are unlikely to be random. In groups that aren't artificially selected at random from the entirety of humanity, error will tend to be correlated with others'.

There are also deep flaws in humanity as a whole, most especially on some issues.

Should we decide to believe in ghosts because most human beings share that belief, or should we rely on rational analysis and the accumulation of evidence (data derived directly from the phenomena in question, not other people's opinions)?