Robin Hanson looks at three recent studies measuring forecasting overconfidence in medicine, law and finance. None of them do very well, and in all three cases they're consistently overconfident in their forecasts. He comments:
I strongly suspect these patterns are driven mostly by customers, i.e., that more accurate professionals would be less successful in inspiring confidence by others in them. If you are a successful professional, that is probably in part because of your unjustified arrogance.
That sounds about right to me.