I think a valuable point has been raised here, that if pilots with 1000 hrs regard themselves as old hands, due to the large number of 500 hr pilots around, then there has been a paradigm shift in what constitutes experience.
A guy said to me once that when he had 2500 hrs, he felt ready for the left hand seat, but by the time he had 3500 hrs, he realised he wasn't.
It is quite possible that a lack of experience in either seat may introduce a level of overconfidence due to a reduced perception of how quickly it can all go wrong and what the likely consequences may be.
The inexperienced, while perfectly competent, may not have yet developed a sufficient perception of risk and the longer the safe operation continues, the more the confirmation bias is maintained that the level of risk is low.
Of course, exactly the same applies to 20 000 hr pilots who believe that they have beaten the odds!