Conventional wisdom is group think and therefore it tends to resist being changed by facts or other real world proofs that it is not true wisdom. 

When dealing with people remember you are not dealing with creatures of logic, but with creatures of emotion, creatures bristling with prejudice, and motivated by pride and vanity.  -Dale Carnegie

he was,  of course, talking about leftists whether or not he was aware of that fact.  The left proves this assertion on a daily basis. 

–Pastor Ward Clinton