... Through vast experience they know, fairly quickly, which new ideas stand a chance of succeeding and which are obviously wrong. Newcomers from other fields, who typically dive in with both feet without the requisite training and experience, proceed to generate new ideas that they think - because of their success in their own field - will be revolutionary. Instead, they are usually greeted with disdain (or, more typically, simply ignored) by the professionals in the field. This is not because (as they usually think is the reason) insiders don't like outsiders (or that all revolutionaries are persecuted or ignored), but because in most cases those ideas were considered years or decades before and rejected for perfectly legitimate reasons.