Yeah even so called experts dont take the right decision 100% of the time, just look at sports how many times have you seen a commentator saying that X team is going to win just to be proven wrong over and over again.
Yes and if applied when doing trades, trading expert also getting mistakes.
But those expert even they are still getting mistakes, already made a good profit out of their profession. Yes, they able to minimize those loss since experience builds them to reached the status of being an expert.